340 vs 383

reliable on pump gas, money isn't really an obstacle, I'll be prepared to spend maybe $2500-4000.[/QUOTE]

Is that amount for just the engine or the whole project? Big HP engine is for not if the rest of the parts are not up to it. Tranny, converter, rear end, fuel system, carb, pump and lines, cooling, distributor, ignition, it's a viscous circle in the HP world.
Big block in A body makes for scarry driving, braking and handling are out the window without, guess what? More $ thrown at it. Oh my, are we having fun yet!!