I'm in the process of putting a pair of 748 forks into my carb 750ss, so I'm going from 54mm bottom yokes to 53mm required for the swap. I was just going to use 1/2mm aluminium shims, but yours look so much nicer. At the moment, I don't have enough material to make shims like that, and they would be awkward to do with my lathe.
I will have a dig around to see where I bought the metal from to do it, but it was about £150 for the yokes milled and the spacers. Out of interest why 748 forks? Or do you not want to change to the newer Brembo brakes?