I second old bag. Run through the basics: adjust the valve clearances, then re-set the timing. I bought a MityVac vacuum tester kit. Easy to use, just hook up to the dizzy advance and pump it a little, see if the dizzy rotates or not. (OR, I guess you could unhook the vac. line at the carb and SUCK on it REAL HARD! ;-)
If no rotation, you need a new vacuum advance module, though this might not be the only cause of your overheating.
Also, a lean condition can lead to overheating. Does it cool down if you give it a little choke?
How is it running? How do the plugs look? Is it too hot all the time, or only sometimes? Did this just start happening?
-Michael
