First thing I'd check would be the points and timing. Make sure the points are in good shape and gapped correctly, then set the timing at maximum advance to 32 degrees before top dead center. If the timing is less than 32 degrees, you'll loose power and can overheat somewhat. If you have more than 32 degrees of advance you will gain a lot of power for a short time . . . right up to the point that you burn holes in the tops of the pistons.
Lots of other things can cause overheating. A few things I've had experiance with include: If the car sat for any length of time, anything from mice or dirt dobbers could have nested in shroud or fins and blocked the air flow . . . leaks in the intake can cause a lean fuel/air mixture, which will make it run hotter than normal . . . missing pieces of tin . . . a bad engine compartment seal letting hot air be pulled back into the engine compartment . . . lots of other stuff, those are just a few off the top of my head.
