1969 dart 10" drums

The 10" drums aren't even made anymore in SBP, you'd probably spend as much to replace the drums as it would cost to covert to disks. Best bet is the 73+ disks. You can get a set of adaptors from Dr Diff so that you can keep your small ball joint UCA's and use them with the later 73+ spindles http://www.doctordiff.com/a-body-upper-ball-joint-tapered-adapter.html

Then you just need the 73+ spindles, or F/J/M spindles. The F/J/M spindles still show up in the local yards because they came on 5th ave's and diplomats all the way up to '89. Just grab the spindles, caliper brackets, and brake distribution block. The rest of the parts, bearings, rotors, calipers, master cylinder, brake lines etc are best bought new anyway. Just head over to RockAuto and get disk brake parts for a '74 Dart.

I wouldn't mess with an aftermarket conversion (wilwood, ssbc, etc) unless I was going to go big, for disks under 12" I would (and have) used mopar parts. If hitting the junk yards isn't your thing, you can get everything from Dr. Diff. If you go aftermarket, you're stuck going back to wilwood, ssbc, etc whenever you need replacement parts. With the OE 73+ stuff, you can go anywhere, and it's not likely to be discontinued because most of it was exactly the same from '73 all the way up to '89. That's a lot of cars.

10.95" 73+ disk kit w/ everything you need for 73+ mopar disks http://www.doctordiff.com/10.95-front-disc-brake-kit.html

11.75" disk kit. This uses all Mopar parts, just off of the later B/R bodies. Needs 15" rims http://www.doctordiff.com/front-disc-brake-kit-for-11.75-on-disc-knuckles.html

I run the 11.75" disks on my Challenger, they're awesome. Although even the stock 10.95" disks will be a big upgrade from the 10" drums.