This thread from the hamb has the bearing part #'s for the conversion.
http://www.jalopyjournal.com/forum/s...ead.php?t=5877
The only thing wrong with this is that your spindles have a tapered transition from the square-back to the spindle shaft itself, a smooth tapered curve. The back-side of the inner bearing (that the hamb thread provides) has a sharp edge, so the two don't mate up properly. I would think the bearing could be machined, or find a different part #? I wouldn't think machining the spindle would be a good idea... Other than that everything fits like it should.