Tony, There is one on eBay you can see by Clicking Here. It would make a mighty fine Christmas present for your 63/64 Cadillac Webmaster!
Poor ol Tony, he'll never buy a 175 degree thermostat even as a gift.
It's not that he can't afford it, doesn't wanna do it or anything except maybe his pride. LOL.
C'mon Tony, bung a 175 in the ragtop..... I F*^#ing dare ya..... PMSL
Mine also runs about a quarter way with a 190 thermstat
Tony. I run a 180 degree thermostat. That is the temperature the thermostat starts to open. Per info on Stant site it is fully open about 15 to 20 degrees above stated rating. That means it should be fully open allowing water flow at 195 to 200 degrees. My car warmed up gives a temp rating about 197 degrees via the digital IR Temp Gun. That is exactly where it should be.
The only thing to add, is I think you should consider a digital temp gage if you do not have one. You cannot guess or assume a specific temperature based on an unmarked temp gage. Finally, the engine is not going to run at 180 degrees if running a 180 degree thermostat. Again, that is the temp the thermostat starts to open. The engine is going to run closer to the fully open temp range. Of course an engine can run MUCH higher than even a thermostat temperature "full open temperature" from many other issues such as timing, low coolant, worn engine, clogged channels, etc.
Tony. You better get up and get to bidding on that 175 degree thermostat.