converting an 8 3/4 to the correct sure-grip

not really good advice. I do not like the Idea of getting rid of the original mopar tapered roller bearings and it IS possible to get a "cone type" sure grip. Green bearings are not as strong. They use ball bearings, not roller bearings. I would not spend a grand for something that is not as good of quality as the original equipment.
The best advice; call Randy's Ring and Pinion. They know the 8 3/4 probably better than anyone. They will give you the best advice. (try googling them).
...(I'll probably get dissagrements on the "bearing" controversy)