So does Wilwood I believe - or at least they used to (I haven't checked recently). Wilwood also had/has kits for front drum brake cars that allow you to convert to disc without having to replace your front spindles. (Spindles for factory front disc are different from the ones for factory front drum.) Others may also.
I used Wilwood on my '69. It was originally a front disc car already. The only problems I had were that even though I bought a "kit" for the whole car, it didn't actually include everything required to complete the installation. I still had to buy some additional fittings to connect all the lines, some 'shields' to protect their aluminum front hubs from the steel wheels, parking brake cable adapter kit, etc...