Ok here again lol. For a well built 331-347 run at least a 185cc head. I prefer the new tfs 11r comp ported 205 heads. They have topend valvetrain components with 2.08x1.60 valves and can support up to 650hp n/a. Run a custom hyd roller cam(for the street if racing and want 7k rpm go solid roller) compression around 10:1,good rods&crank,tfs r intake(or comparable),90mm tb and mas,42#inj,at least a 255lph pump,long tube headers,good ign system and a dyno tune. Easily capable of 400+rwhp. The 170cc tfs heads and topend kit are fine for a milder build. With a 331 you can still make 350 or better at the wheels with that kit. The difference between the two would be around .7-1.0+sec in the same car(depending on the extent of the eng build,driver ability,etc) tons of tfs topend kit Strokers running around. If you want more than that it just takes more research,time, and of course $$
Thanks! Looks like I'm gonna stick with the kit then... 350 at the wheels is plenty for my needs! Better yet, it probably means high 300s at the crank, which is great bragging material for whatever that's worth. I'll add a 70mm TB, BBK long tube headers, shorty H-pipe, and the flowmaster 44 cat-back I currently have on the V6. Plus a shiny new built T5.