Don,
I don't use thermostats, I just use washers in the thermostat housing. I just adjust the diameter of the hole in the washer to regulate the time the water is in the radiator. So if you go with that theory, you can use a 1" i.d. in your washer and a 1" id. in the radiator hose. If this doesn't make sense I will try again. You know about my writing
Ken