Hello grossgary.
It seems to me, if the head gaskets were blown, than turning the heater on would not help at all, the engine would still overheat. I think that the fault is in the radiator, but maybe it is just a wishful thinking… I really like that car. I am going to the dealer tomorrow and if he refuses to do it himself, I plan to buy the block leakage test kit at my own expense and run the test myself.
Any more pointers?