So here's the deal. I have a 96 RCSB 6.0l swap. My current setup is:

2003 Lq4
243 Heads with cometics .40 gaskets
Comp XR275HR cam with 918 springs and hardened pushrods
TBSS intake and 87mm dbw throttle body
42lb injectors (have ev6 plugs with ev6 to ev1 adapters)
Stock nnbs return less rails with corvette regulator/filter
Walbro 255lph pump in the stock sending unit with stock lines

Backed by a 4l80e with around a 2800 stall and 4.10 with a 26" tall tire, truck runs high 12's in the 107+ mph range. Everything works great, duty cycle on the injectors maxes out around 68%. But I want high 10's now, and I have another project that I can put this motor in, so turbo build it is.

I've been reading constantly on FI and I just can't seem to get the fuel system nailed down. New combo will likely be:

2004 Lq4, stock cam, head studs, ls9 gaskets, Comp 918 springs (already have) and a borg s475 with 1.32 a/r setup, air to air intercooler, flipped truck manifolds or shorty headers (have both). Shooting for 600 to 650 rwhp.

I'm struggling a bit with what to do on the fuel side. What's the best way to go here.

I'm planning on running 80lb/hr seimens injectors.

Dual 255's or single 400 or 450? I hate the though of running 2 pumps when I can just buy one big one and use my 255 for another project. I also would hate to have one pump **** the bed (on a dual setup) and run lean.

What fuel rail setup? I have both a nnbs intake and return less rails or an older truck intake of an 03 with return style rails.

If I go returnless, which seems to be preferred, how do I bypass the stock regulator properly? Is there a plug or kit that's available or do the rails need to be modified?

If I run dual 255's on a Hobbs switch, do I need to worry about the replacing the stock fpr? I've read some use it and say it's actually boost referenced.

I'd prefer to run a 400 or 450 walbro, what's the best way to set this up? Thanks for any help. I keep thinking I've got it figured out the second guess myself and start over. This is my first FI build so bare with me, thanks.

 

A single pump will get you to 650hp no problem.
Im planning a fuel system for my truck now. 650hp or so is my goal. i am planning a return style with a single walbro 450, -8 feed into one rail, a crossover, the other rail, then a regulator with a -6 return.
i never have liked the idea of dual pumps with one on a hobbs switch. seems like a lot to go wrong and easily burn up a good engine.

 

Walbro 450, stock lines, find an early flex fuel return style rail(03 tahoe/suburban) from the junkyard. The rail will be stainless steel and the regulator will flow much better than the non flex rails. This is what my setup consists of and I have had my 5.3 turned up to 20psi with meth and still had plenty of fuel. The 80's were at 70% idc on the 20psi log

 

Awesome, thanks for the replies fellas.