Anyone with a couple of brain cells to rub together and some machine tools should be able to adapt a modern bypass stat to the 261 housing. Start with a thick chunk of aluminum and whittle away anything that doesn't look like what you want. The trick will be finding one of those thermostats that opens at less than 195 degrees.
Jerry
I agree. My son does engine management for a team that races Daytona Prototypes in the TUDOR United SportsCar series. They recently adapted a bypass type thermostat to their LS based race engine and he is sending me the drawings and a part number for the thermostat they used which is a 180 degree unit.
I think I can modify a stock lower housing fairly easily to get the bypass water out. The trick is going to be getting the water back into the water pump in an elegant manner. There is not much room to work with.
