I believe that the 8/1 type bronze backed upper was a recommended upgrade for the heavy flywheel 6/1, but not factory equipment? But either way you are correct in that the bronze backed upper is the one that should be used. I would not pull the other type out or service just to change it over but would certainly use a bronze backed upper in a heavy flywheel engine IF I had one available.
Sorry to hear that you have had issues with Indian bearings. My experience has been that India bearings and rings are very dependable parts. As Gary said unless purchased old stock any bearing or ring you buy for any engine these days is likely produced in India,, at least if purchased in this country.
Sleeman claims to spec superior stuff but I haven't seen any evidence of it. What I have layed my eyes on is same ole India parts taken out of the brown paper wrap and placed in a purdy box,,,,with a huge price tag.