10 X 2.5 in rear drum brake assemblies for 8.75 diff.

Glad to help. Just to be clear, I agree with Dana67Dart. My first contact would be Doctor Diff. Tell him what you're trying to accomplish, and he'll steer you in the right direction. I've never purchased from Moser, but I've done business with Doctor Diff and have been completely satisfied. He wants to be contacted by email or text only. I've read complaints on this forum by folks who tried to contact a different way and weren't happy with the results. Dr Diff shows 8.75 housings and 10x2.5 brake assemblies as out of stock, but it doesn't hurt to ask. As many here will attest, he's the first one to go to.
One other thing is that the 1.75" brakes will work, and you have at least some of the parts. They are a bit of a oddball setup and parts (drums) have been hard to get off and on. So, depending on how you'll use the car, the 10x2.5 are likely the better overall choice.