70 Duster front drum to disc conv.

I have a 1970 Duster 340 that has manual drum brakes in the front. If I am not mistaken it should have disc brakes as the standard option. I would like to convert them back to disc brakes and was looking for suggestions on how to go about it. Is their a good after market kit that I could pick up to fix the problem. Or would I be better off finding a donor car and taking them off it. Keep in mind my car is a real H code car and I don't mind making some improvements from stock as long as they are not too radical. It’s not matching numbers but has a date code 340 block, the original heavy duty 4 speed trans and 8 3/4 rear with 3:91 gears. Oh and I want to keep the 5x4 small bolt pattern that the car has.