Using mustang rotors for 4.5" bc

I knew the Mustang stuff was made by KH and both systems used the same pads and pistons and stuff like that, didn't know about the rotor thing though, very cool! What do these seals looks like? Are they all rubber? What about having them made? There's some rubber places that are not totally unreasonable. I'd be into doing this and putting up money for the seals if I thought it was all going to work.

For example, Karr Rubber made some window rubber for a van I own on behalf of a group of vanners. It was like $1400 then $85 a set for each person. Small seals would be much much cheaper.