Any coolant odor from the exhaust, or bubbles in the radiator? It's beginning to look like you might have a head gasket leak. Do you have a way to put a little pressure in the radiator? If you're running an original radiator and/or heater core- - - -emphasis on A LITTLE- - - -like 4 pounds or so! I use an air hose and a pressure regulator for a paint gun. Leave the pressure on overnight, pull the spark plugs, and spin the engine with the starter. A leaky head gasket or a cracked cylinder head will squirt coolant from the plug hole where the leak is.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!