4.3L V6 to 6.0L/LQ9 or 6.2L/LY6 swap for a 2003 RCSB 2wd Silverado

[atomantiumx]

Planning to do a engine swap sometime this year, but now I'm having a hard time deciding on a particular engine. I want a engine that will give me roughly 400-500 HP/TQ one way or another. I am aware of the interchangeability of the Gen III/IV LS engines and I feel pretty set on a LQ9 or a LY6 engine, as the come specifically from the trucks. I am open to other engine suggestions as well. Just trying to make the most out of the swap. I just want some seasoned input on the pros and cons of what engine to go with and a idea of what parts I could carry over (if any) from my 4.3L setup.

I'm leaning more toward finding a engine combo with a 4L80e or a 6L90e tranny. The 4L60e I have has only 121k miles on it, but I'm pretty sure if it won't hold up very long with a 6.0L stuck to it unless I have it built. I am also aware that the wiring harnesses and tooth reluctors differ, but which engine would get the most bang for my buck in the long run?

[907 Chevy]

I'd wait for the Gen V personally. All new architecture and direct injected. The performance potential and fuel economy of the up and coming generation of gm smallblocks is going to leave gens 1-4 in the dust.

[atomantiumx]

I've read some tidbits on the Gen V's... Those will still take some time to be accessible and reasonably priced. I will probably hold out for the redesigned 2013 model to get a Gen V platform.