thermostat temperature

with aluminum heads your car will run better at a lower temp.
with a 160 thermo in mine, it never goes higher than 175.
you have a little more colder weather than i do so a 180 should work well for you durring the winter and durring the summer try a 160.
 
You could try it, but based on the assumption that your gauge is correct (is it?), I would look into other problems in the cooling system. Things to consider are:

1. Are you running more than a 50/50 mix of antifreeze and water? Anti-freeze is not efficient at removing heat from the engine, its purpose is to prevent coolant freeze-up and to inhibit rust.

2. How's the radiator? Is it large enough for your application and in good condition?

3. How are your belts and hoses? Belts can get old and slip on the fan/watr pump, and hoses can rot from the inside out and impede coolant flow.

4. What about the water pump? The vanes can wear/rust down over time.

5. Where is your ignition timing set? That can cause excessive engine heat too.

6. Is your carburetor jetted too lean?

I am sure there are several other items that you can think of that are worth looking into also.