[ColoradoCobras.]

I'm surprised no one has mentioned handling characteristics in here as well! A small block 351 will make plenty of noise and plenty of power for a 2400 lb car and handle sooooo much better than a big block.
In Colorado our roads are twisty and sometimes with steep drop-offs. The last thing you want is your Big block engine to "push" a corner that has a 2500 foot drop-off!
The Small Block gives a nice 50/50 weight ratio from front and rear tires. I would rather have a little less "wow factor" under the hood than the "WHOA! factor" heading into a less than friendly corner!