I feel your pain, I'm doing the same thing with a 65 Barracuda. The best it came with is drum brakes, sbp and a 7 1/4. I ended up buying a 73 Dart Swinger parts car just for the upgrades to the disc brakes, BBP and 8 1/4 axle.
Great looking dart though. You have an excellent starting point. Much better than most of us start with. Keep us posted on your progress.