Yeah, the 6.0 is the way to go... stock lq4 will make more power than a 5.7 ls1.
don't waste your time with block huggers or shorty headers, get some long tube headers they make good power.
i was looking at doing L92 heads on my LQ9 build, but i didn't want to give up too much low end torque, if i was building an all out race truck just for WOT in the dunes, i would have gone for it, but i'm building my truck dual purpose for racing and for crawling..
Look at the test they did in the hot rod magazine, they picked up a buttload of HP but sacrificed a bit of low end, and shifted the whole powerband higher in the rpms. i'd be loving it in the dunes, but not so much at 900 rpms trying to crawl the thing.
i'm pretty damn happy with my LQ9 6.0L, got a custom grind cam a little bigger than the TR224 i recomended.. it should be good for about 450hp.
Got me a 2nd place trophy at the mud drags the other weekend, the only truck that beat me was this green longbed that had a 720hp zz572r.
we were only racing 125' but i think i put up a pretty good fight for being way underpowered...
http://www.youtube.com/watch?v=Vufd04yIb7A