Thanks Joe! The screw holes on the bottom plate are not center and one can install so the felt rests more on the head or slightly off like the one pictured. My RB has the plate reversed from the one pictured above.
I can just loosely measure, grab intel from my RB, and eyeball my BK felt replacement. I was hoping someone had a method, high school protractor angle or something. The felt is Gretsch and came pre trimmed for the assembly. One side is cut longer than the other. No instructions.