Personally, IF you can find the parts modifying a factory stick setup it is usually the easiest way to go but as mentioned finding a donor car may be the biggest problem.

The main thing I wanted to mention for those of you who have not done a MOPAR auto to stick conversion is the crankshaft of the engine. My experience has been that most 50's thru 70s MOPAR engines that come from automatic equiped cars are NOT drilled for a pilot bearing or the long input nose of the Chrysler stick transmissions.

On the last few MOPARs I've rebuilt I had the machine shop drill the crank before they sent it out to be ground just so I had the option down the road.