big block or small block

[Derek69SS]

Between the two choices, I'd prefer a mild cammed 454 with an overdrive trans and something like a 3.31 rear gear. Bigblocks just look "right" in a Chevelle, and if you gear it right and keep it mild, you should be able to get 17-18mpg on the highway and have enough power to have some fun with.

If the budget allows though, I'd suggest a 5.3L or 6.0L LS truck engine instead... they're not too difficult to swap if you use an automatic.

I'm working on an LS1-383 stroker/T56 six-speed swap in my car, but there's nothing cheap or easy about that, and the 6-speed requires a lot of cutting.