G'day Joe
The thing you've got to watch is the back focus consumed by the OAG and Moonlite together, as neither are short. I believe the recommended back focus for the f/6.3 reducer is 105mm but I could be wrong.
The thread on the camera side of the reducer should be standard 2" SCT thread, so as long as the OAG has M48 male on scope side then that adapter should work.
What OAG are you looking at?