The exhaust manifolds are different than full size trucks. Lots of guys doing LS swaps use the Trailblazer SS exhaust manifolds because they actually flow pretty well and coming off a trailblazer means they can fit on a narrow framed car/old truck.
Cam and full bolt ons awd with just the spare removed I went 12.6 .
A lot of guys do way better with some lighter wheels and some weight removed, it's easily achievable.
A built trans is recommended and probably the most expensive piece of the puzzle.
Do you still want the truck to be the same as it is today? Or do you want to make compromises? Like it has been said you can do H/C/I + stall + exhaust and it'll probably be a fair bit rowdier; or you can boost it (which will cost more) and the truck will be more civil.
I went with boost to keep the truck feeling "normal". Granted I bought a small stall, built trans, headers, intake, LS9 cam and LS7 lifters, springs, pushrods, fuel mods, etc to support the blower.
There are many different ways to skin these heavy pigs.
Is there a used buyers guide form these things? I am a heat duty mechanic, but it'd be good to know what to look for. There a few around, some with higher mileage. Should I be scared of them? I'm ready set on no modifications, want a rear dvd for the kid, and am selling my 1992 Typhoon for it.