2 style radiator caps- where to buy what I need

I don’t know- toolmanmike- show me a picture of your radiator cap and what you run? I went with #14lbs but see my Demon340 is #16. Maybe I’m just too low. I cannot find the factory cap pressure for my altitude which is just about sea level or like 70ft above. I’m used to #16 or #18 but the radiator had a #14 on it before the rebuild with no issues.
Damn “Flat Earth people” must be right.