IMO the best chevy engine is the 350 hands down. Its pretty much an opinion thing wich one is best, but the 350 drivetrain is cheap to mod, and lasts unlike any other ive seen. They have the largest market for aftermarket parts, and the 350 in a 70's monte carlo, is still the king of dirt track roundy-rounds, and has been for many years.
Mine has been rebuilt twice, and this year it turned 36 years old. As old as it is i would trust it over ANY computerized car on the road, because its so sturdy and simple. To get the entire engine rebuilt and set up to pump out 400 HP is only 500 bucks. 350/350 FTW!!
I still say a 2.8 is a good motor. Ive tried to tear a few of them up, and they simply wouldnt die. Ive ran them dry on fluids, pushed them past readline time and time again, and they took it. I dont see why everybody complains about 2.8's. The ones i had were all original high miles 80's motors, that wouldnt blow up, not that the attempt wasnt made.