[Ziegelsteinfaust]

If you have to use a 4.3 the best version is the 95+ Vortec. A decent cam swap with bolt ons, and your above 275hp at the crank. The balance shaft is actually desired for most circumstances as it helps smooth out the split pin odd fire arrangement or what ever is the proper term. It only cost 7hp average from what I read. So I would think before going with earlier versions.

I have to ask why are you going with a 4.3? Personally the trucks I have had that had them or friends that had them. Either work or personal. It either got the same or worse mileage then V8's.

If mpg you after a 283, 307, or 327 all work better. For power a well built 350 will get the same mpg, and have better power.