Beaver:
I haven't had it boil over yet. I think the main problem with the way it runs when it hits 180 is the lack of a spacer plate under the carb. Either that, or the coil is about to die.
A Radiator flush is on the list of things to do, but it is pretty far down the list.
Ken:
I haven't torn into the thermostat yet. Once I do, I'll check to see what it is, and get the right one if it's not.