Owned an '02 Tahoe Z71 4WD for two years so far. I'll never love it as much as I loved my Caprice wagon.
But the Z71 is FAR MORE USEFUL. Nevermind the more useful cargo hold for now.
In heavy rain & snow, thanks to Auto4 & 4Hi, the Z71 has driven over / around / through stuff that stymied the Caprice.
That said, I drive the Z71 in abject fear of emergency lane changes.

When I first bought the Caprice wagon, I felt the same fear.
After upgrading the springs shocks and front swaybar, it became far more confidence inspiring than normals could accept.

I've no desire to lower my Z71 by more than an inch - the extra ground clearance has come in VERY handy.
But it'd be nice if it could also be better at emergency lane changes. Right now it's like driving a reasonably well-damped waterbed.

I also don't want to get rid of the front torsion bars, although I'm pretty willing to use stiffer ones.
Interesting note:
the front jounce cushions are so gone, that my mech had to show me TWICE - the second time with HIS Tahoe - to convince me .
So I'm looking to upgrade these too. Better if they're OE from a better-handling or heavier-duty GMT relative (Z56?)

Does this have to be more complex than a 6.2L with holy heads?

 

Reasons for not getting rid of the torsion bars? Atomic Fab coilovers are a tried and true solution and can be dialed in pretty good.

this may not be as complex as a 6.2 with holy heads. Do you have a front sway bar?

Personally I would do the Atomic coilovers and lower the truck a half inch or an inch. Even that little bit will drop the center of gravity and feel better handling wise.

 

Haven't yet learned enough about GMT800 to reach the point where I feel comfortable about reengineering it with coilovers.
Front and rear swaybars. Before I lower it, I DEFINITELY need to research front and rear swaybar options.

Lowering sounds VERY appealing. If money were no concern, I'd lower it enough to have to relinquish my Z71 badge.
But there've been more than a few times where the extra ground clearance saved me, and allowed me to be helpful to others.

For now, stiffer swaybars at least seems simpler and more straightforward than lowering.

 

Front sway bar can be swapped with one from a pickup with the camper package. Unsure of the RPO code. You can also use a PPV package Tahoe front and rear bar. Front bar might actually be the same, but I am certain the rear bar is thicccccer

Rear sway bar from the H2 is a bolt in upgrade, but you will need to use the H2 end links and bushings. This is a bar thiccer than a bowl of underhydrated oatmeal

Can you weld?

outside of those couple oe options, you're looking at Hellwig and Eibach for sway bars

springs are fine, imo. The Bilstein 5100 shocks for our trucks have digressive pistons, and are pretty stiff. They suck for choppy off-road for the exact reason they work well to stiffen up the truck- they resist suspension impulses until they are into the bleed thru portion of the stroke

Its been more than a decade since I messed with the jounce bumpers and research, but I just pulled them off my 02 Tahoe Z71, they haven't been used in quite some time because I had cranked keys and the truck didn't ride on them. I'll send them to you for cost of shipping

 

Didn't have a clue there was such a thing as a Silvierrado camper package. Certainly never seen one.
My first instinct is to guess at PPV / Z56 suspension stuff for my Tahoe, but I don't yet know enough about the similarities vs the differences.

I've also wondered about the similarities / differences between Tahoes and H2s, but I suspect the H2 is more like a 2500 than a 1500?
My definition of 'OE upgrade' would be very satisfied to use any H2 steering or suspension parts proven durable by the past 15 years.

Can't weld, myself. I do know talented mechanics with considerable welding experience.
I'm all for any welding that doesn't remove functionality, until I determine that function to be either useless or detrimental.

When it comes to steering and suspension, though, I'm open to aftermarket stuff that works pretty much the same way as OE.

The few times I've been 'off-road' were as much about snow as dirt. If Bilstein 5100 works for trepidatiously slow off-roading?
Do Bilstein 5100s work well on badly maintained roads? I'm VERY accustomed to 9C1 / PPV sedan stiffness, if it means anything.

Presently lacking jounce bumpers, having them would be an upgrade, so I'll get in touch with you very soon ...

 

The Bilstein 5100s will have a much harsher response to initial impact, but once they get moving and the pistons allow bleed, they are good shocks. So they take bit hits well, but the little nuisance bumps are certainly felt

I have a set I just pulled off my Tahoe, but they are for 2-3" taller ride height. You'll need cranked keys and rear spacers to run them. If you want them I can save them for you, otherwise they going on market place and someone's agent is gonna "pick them up and ship them" for 300% asking price 🤣

H2 vs Tahoe isn't that drastic of a change, but only in the rear. Some things need to be relocated via cutting and welding, but the rear axle *essentially* bolts in, the rear sway bar can be swapped and the 03-07 H2 even uses a 4L65 lol

Lots of stuff up front doesn't swap, because it is a 2500 up there. The 2500s and 1500s have a lot different up front. Essentially everything is a different size or shape and not a direct swap

the RPO code for camper package might be Z85. Take some calipers with you to the yard and start measuring if all else fails

 

FYI, I looked here
https://decoderpo.com/pages/Z.html
and found the following:
Z76 CHASSIS, SPECIAL COMMERCIAL CAMPER PACKAGE
only one entry

Z85 Suspension Package, Standard
Z85 Suspension Package, Handling / Trailering, Heavy Duty
Z85 CHASSIS PACKAGE, INCREASED CAPACITY
three entries means it was available on three different model vehicles, or the same vehicle across three generations, or some combo of both.
Point is I can't tell which (if any) applied to a GMT800 - but someone else likely can.

I'll decline those Bilsteins, as I want to stay at the same height, or go down a wee lil bit, not up, not one mm. I can only just barely make it into most garages in NYC.
That said, that description sounds like those Bilsteins feel like they treat the road similarly to 9C1 Bilsteins.

I'll need to learn / study more about Tahoe vs H2 rear similarities / differences before I let anything get cut or welded.