Which heads?

O.K, ratrod, lets just say we were talking cams instead of heads. Would a .600 lift cam with a 320 duration be recommended for this particular project??? Why not?? A cam this size will outflow a 340 size cam?? If more flow is better, then why not a cam of .600 lift and 320 duration?? If you say "too much" cam for a stock 318 and stock converter, and will kill performance, I will say why?? More flow, right?? This is why I want the right head choice, and the 308's may end up being the right choice. I just want more perspectives before I start tightening bolts.