I have a set of wheels from an 85 SJ Sport that match your description. They are bolt on, not sure if your's originally came with those or quick-release.

I also have a SR Laprade seat post that matches the one TheGoldenBoy showed above. I'm not sure if it came from my SJ or my 1st mtb, an 84 Miyata RidgeRunner. Probably doesn't matter, but it is short, 26.8 and dark grey with the flutes as pictured above.

I do really like these hubs but since you're trying to restore your bike to original spec I could be convinced to keep them together with the X28 rims. Let me know if you're interested in this stuff.