Cam Bearing Interchangability

I've been following this with a great deal of interest. I noticed that in another post, Brian Perrenot points out from personal experience that the bearings will not interchange; & looking at the block bore IDs as posted, he's right.

Since the late bearings have a smaller OD, I suppose steel sleeve rings could be made & installed. Failing that, it appears that either A) a custom billet cam would have to be made; B) an earlier '58-'60 Isky/etc. blank, or roller, would have to be located; or C) a stock early cam would have to be reground to the desired profiles. Hmmm.

I don't suppose that the Isky catalog had any more specific details??