I've seen those bearings, and the inner bearing includes an extended section of the race that's at least 1/4" wide, and maybe a bit more, that's designed to give a replaceable surface for the seal to contact. Machining a spacer that width would allow a standard-width bearing cone to be substituted. It would probably need to be casehardened to prevent the seal from wearing a groove in it, although seal surfaces on a spindle aren't usually hardened, so that might not be necessary. A very slight space-out of the hub and brake drum shouldn't cause a problem, as long as there's adequate room to tighten and cotter-pin the spindle nut, and the brake shoes still have a drum surface to ride.
Another possibility might be to machine a larger diameter and/or deeper counterbore in the hub to accept a bigger cone/cup pair, and machine bushings to adapt the bearings to the spindle diameters. a suitable-size grease seal would also have to be researched if that option was chosen.
Jerry
