Try putting a T fitting in both heater hoses, with a small tube like a 1/2" diameter connecting them. This will create enough coolant circulation through the block during warm up to prevent hot spots from forming before the thermostat opens up.
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!