Since I first posted 76GMC, I've been picking up a bit of info. I pulled a valve cover to get my head #. It is 10114156 w/ 118 cc combustion chamber. You could hold a party in there. Also, best that I can determine, the piston does have a 'dish' in it, probably in about 1/2 the surface area of the top of the piston. I'm not into pulling that motor out to remedy that, however.

Chilton lists the HP of that motor at a whopping 230. That's hardly enough to pull the motor around by itself, let alone that 3/4 ton body. I will say that the Banks Power Pack I installed made a huge difference in driveability, but newer 350 mpi's can easily keep up with me, with a boat in tow and blow my doors off unloaded.