Kevin, know how you had the head ported for better flow? Now take off the water pump, open the housing and do the same. Bore the inlet and outlet to maximize flow area. Then go find a thermostat that opens as far as possible, not just one that opens earlier. And no, they are not all the same and can vary greatly depending on brand. You may find putting an inline housing and thermostat works better than one in the stock location. Next, run the system at high pressure all the time. Most heat soak problems come from letting off the throttle reducing coolant flow and pressure. Reduced pressure equals lower boiling point, and steam bubbles don't cool well. An accumulator pressurized to almost match the radiator cap relief pressure, will keep the system pressurized all the time. You have the perfect opportunity to explore as your bike is on the dyno now and you have bottomless pockets.
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