Disc brake conversion wheel hub sizing

I just measured 75 model a-body disc hub to be right at 2.78 inches.
I'm thinking since the wheels you have do fit your drum brakes spindles hub, keeping those spindles with disc brakes, like scarebird does, may be the only option.
Ah, so thats what I was wonder about when I looked at scarebirds rotors, there are no hubs in them. So I would just re-use mine, which is fine by me except my drums are a miss match. One drum has the separate hub, when the other drum has the hub fixed to it. I looked on Rockauto and other part stores but don't see where I could purchase another hub, but have to believe they are out there. Maybe scarebird has some as well..
Thanks all for the replies! Maybe there is hope after all.