Once you have determined what you actually have or are considering buying, then can you determine what works with what.
I would choose the 96 harness as it matches the non egr intake set up. OBD II is also easier to modify for cam, emissions and O2 also. You can always grab a OBD II 5.2 auto pcm for cheap. If you are mating 5.2 and 5.9 stuff, you will have to swap converter as well. 5.9 neeeds counterbalance weight.
As far as making the 44RE fit the early A body, look for our thread about installing a 44RE in a 64 Dart for pics of what needs to be modified. You will also want to get a V8 center link for steering, car pan(5.2 & 5.9 magnum are same pan) and drivers 273 exhaust manifold or headers.
The 96-97 Ram truck pcm and harness work well for this swap as they have separate sensors for temp, oil and tach as they are not ccd buss like the 98+ Rams. Ie they have double wire oil press and extra coolant temp to run gauges.
The pcm can easily be flashed to remove evap codes as well as making it a one O2 sensor system to run with out a cat.
We are currently working to convert push button and old floor shifters to late model cable trans as well as a protorype header. If you have any other questions and want answers rather than guesses, give the shop a call at 541-955-0363 9-5 pacific time and I can answer all your questions. Evan