Nice job. You have done a great job at making your caliper mounts I can only hope mine come out as good.
I am looking at doing the same to my 56 6100
I think that I have found a rotor and caliper set that will work. They are 15” rotors and have the same 6 on 6” bolt pattern as my current drums. So I think that they will right to my hub. They come off a late modal Isuzu step van that has the same 6 on 8and ¾ bolt 22.5 bud wheels as my truck. This will be a new section in my truck build soon.
I will add more on the donor vehicle as soon as I talk with the mechanic at the laundry that uses these step vans.