Disc Brake donor vs Disc Brake kit....

For those that have followed my posts, this is a continuation of my many questions regarding rebuilding my 1966 Barracuda. For those that have not, here is where I am.

I recently purchased a 1976 Duster that I was going to use for parts (the 8.25 rear end, and the disc brake setup). I have the car, and I was going to pull those parts off and sell the car (was going to put my 7.25 rear and my front end on it so that it will roll) but now I am wondering if I should think about selling the entire car and taking the money and purchasing a "kit" for the disc brakes? Is there a kit out there that I can purchase that will allow me to upgrade to the larger bolt patterns, plus all the parts needed for disc brakes? Or should I use what I have on the donor car? I have read about the scarebird kit, but I don't think that would change my bolt pattern (I currently have the small bolt pattern) or is there something I can do to change that?

Any advice would be appreciated!!

John