I seem to remember seeing an H-shaped heater hose connector with a small-diameter crossover tube that bypasses a little coolant back to the return line even with coolant flow to the heater core shut off. This would accomplish some positive flow from under the thermostat housing to the water pump inlet and assuring coolant flow through the block.
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!