I have a 71 350 in my wagon, which is a bit heavier than your 78. Very similar build, probably 325 hp, runs high 13s with a 3.42 gear. Simple, reliable, responsive, reasonable economical, and fun to drive. I shift at 4600, no need to wind it up and break stuff. Here is a link to the specs if you are interested,
http://72.22.90.30/phpBB2/viewtopic.php?t=28012