they will be machined out on a lathe, its not possible to be out of balance, this is how regular wheel spacers are made
Glen, get me some drawings. I know someone with a CNC mill. No promises, but that would solve your off-center hole issue.
Honestly, you'd be better off doing the flipped calipers or the 5/8" spacers, but the true life is in the journey, not the destination, so send me some drawings!
