Bought a set a rebuilt heads, Worth it?

IT could be a head gasket. When your car is running, look into your radiator to see if there are bubbles. Do you have any water in your oil or visa versa? A cracked head is unlikely.

Well if your plugs are greenish it could point to coolant burning...have you checked your fan? Assuming you havn't switched to an electric fan, check the fan clutch. Mine would spin easily hot or cold. I changed it and presto, no more overheating. It will not spin more than a 1/4 or half turn when pushed with my finger.

well, with good compression this looks like a tricky problem... are you pluming out "thick" condensation out of the exhaust pipes. this will stay in the air longer than typical exhaust, and smell kindof sweet. Assuming you have good headgaskets (not saying that you do) it could only be three other things, a leak (heater core, hoses) cracked head, cracked block... respectively. you could be just overheating also... does your radiator "fins" look good with no noticable deposits on them, and is your fan working properly at all times? (fan could also be too small) that should give you a few more ideas, good luck... also try a leakdown test...