PerformanceTrucks.net Forums - Engine, Cam and Misc Questions

I've done allot of searching and comeback with allot of information but still Left with some burning questions.
My current set-up is a 2001 Silverado 5.3L 4X4 W/ LTs and 1 cat (but will be changed to have dual cats), intake, Tune, 20" GM wheels, 3.73 gears and 160K miles. I will try to get the dyno chart posted tonight.

1st Cams:
I had never given much thought to cams until recently and I think it is the perfect solution to my desire for more power and will tide me over for a bit. I haven't given much thought to cams because I know these trucks are engineered to a certain Hp and when you start messing with things, other things have to be changed or start breaking. But I think I can make some changes without too much worry.

I would like 20-50 more HP, Make good power and torque through-out the rpm range, maintian some resemblance of reliability and Gas MPG. I also want to Idle semi-smoothly and not shake the whole truck. I am not too sure yet if this truck will go back to DD duty or will stay as a every couple weeks weekend hauling duty.

I've only ridden in one truck with a cam and I don't know the specs. It was an 04 2wd, when we raced it got me on the whole-shot but then I was even paced with it.
I don't plan on a Stall until the tranny goes, but with the added power that will probably sooner then later. Also I will use the power most out on the Hwy.

These are the cams I am looking at:
TR TRuTorq Level 1 - 219/224 .609/.604 115 LSA
TR 220-112" - 220/220 .551/.551 112 LSA or 114
TR 224-112" - 224/224 .563/.563 112 LSA or 114
Texas Speed 220R 220/220 .581"/.581" Sleeper Camshaft
Texas Speed 224R 224/224 .581"/.581" Camshaft
Texas Speed 228R 228/228 .588"/.588" Camshaft
Comp 273LR HR12 54-457-11 - LSR
Comp 269LR HR12 54-456-11 - LSR

I am lost on the 112 vs 114 and I know I will need new pushrods and springs, but I am lost on springs.

2nd: Engines
Eventually I would like to Swap in an LSX (1-2 years, but start gathering parts this summer), I was going to do a 6.0, but seeing as they are becoming scarce in low mileage trim and I don't see the point to doing the swap 2 times. I was originally looking at a 454 N/A, but now I think that after a year or so I will go S/C to turbo. I would like to go ~ 10.5:1-11:1 CR as to run pump gas. If I do go FI, would I need to change the pistons out when I go FI to lower the CR?
I would like to get 500-600 hp in a N/A state, but if I plan to go FI down the road, would a 376-427 be better? (thicker walls, lighter rotating assembly)
Can I make that kind of power with gen III heads and intake (cathedral port)?
I would like to stay as close to "stock" looking as possible.
Will I need to go to the LS2 style knock sensors?

3rd: Misc.
If i go to the 05+ fans and radiator, do I need to change the radiator support at all? Has anyone used the 34" fans and radiator from LMC?