I'm using the AL Lucas rear caliper from a FWD B5/B6 on an alternate platform (Merkur XR4Ti). I've got it mocked up as shown below but it's going to require a 18mm spacer to turn the 20mm offset caliper into an effective 38mm offset. Any chance a 38mm offset bracket exists? I ask this since a 38mm offset bracket does exist on the Mk4 Jetta, but that bracket is designed for a smaller rotor.

I'm happy hunting for stuff if you've only got guesses on what might be a match.