How do you figure out what bezel might fit on a different watch?

So, I've got this Heimdallr that's homaging the Citizen Promaster. I want to heavily modify it, and one of the things I want to change is the bezel insert color. But this bezel has a very oddly sized insert, 36mm outer, 30mm inner diameters. Hard to find just normal colors, let alone different colors. Plus, the bezel is odd to turn because of the large spots with no grip. So I'm thinking about getting a new bezel that fits an SKX insert, but I have no idea how to figure out what bezel might fit on this case. Anybody have any clues for me?