KH Discs vs 73+ Discs

So, I have a friend with a '67 Dart that wants to do a suspension rebuild and update his front 9" drums to disc brakes. He's got a friend of a friend who may offer him a set of 73+ disc brakes with 10.75" rotors and 1 piston calipers. He's also interested in my KH disc setup and he was wondering what would offer the best stopping power. I was thinking the KH discs due to the larger rotors and pad surface area, but I'm not sure.

Currently, the guy is running small bolt pattern all the way around. He's thinking about replacing his rear end and he could either take some of my sbp 8 3/4 stuff (axle, 10" drums, ring and gear, differential, etc.), or he has a line with the other guy on taking his 8 3/4 stuff (B-body with A-body perches, axles, and 11" drum; no center section). I don't really care if he buys my parts or not, but I just want to help him get a good and safe car.

Personally, I think he should go with the bbp stuff as it will give him more options on brake setups, wheels, and tires (he talks about potentially autocrossing the car in the very distant future). What are your thoughts?