where to buy front disc conversion kit 65 dart

Many posts, so search. The conversions mentioned are to the 1973+ factory disk setup. Your current wheels won't fit the bolts. The 64-72 factory disks were Kelsey-Hayes, but parts are very rare now. A guy here sells a nice refurb setup for ~$900. Wilwood is a common kit, but ~$1000. Scarebird is the cheapest, using common Toyota and Chevy parts.

Smart to change to a dual MC at the same time. A 1973 cast-iron 4-bolt would work, or get a 2-4 bolt adapter plate ($30 ebay) and use any later 2-bolt aluminum (many here use 80's Dodge truck). One place kits that for $90. If you don't have a booster, a complete kit is ~$140 (ebay).