On my frame mountings, I'm drilling out 3 blanks, the third to serve as a jig for the next time I encounter the same configuration. I'm swapping them with another guy building bikes with GEBE kits, but pocket rocket engines.
So far I have 5 jigs, and you can even see how the manufacturers in China are merely changing the paint color/decals, because the spacing on those two holes is major clue.
I would think the same would apply to anybody doing that frame mounting technique as a part time hobby, regardless of which type system used.