All 8.25" rear axles were LBP. So, the brakes on that axle should be 10x2.5" LBP drums. There should be no need for 10x1.75" anything. And on that note, you can't use any SBP stuff with that rear axle, not the backing plates, not the drums, not the shoes. The flange offset is different, you can't mix and match parts and have everything line up.
So, the real question is, why are the 10x2.5" drums "too wide"? Because those are the standard drums for that 8.25" rear axle.