Positioning aftermarket/newer seats has to be done with your butt in them to get a feel if they are placed correctly.
The driveshaft tunnel in a Mopar is usually NOT centered in the car, so you cannot align the seats to it.

When I put the pair of '80s BMW seats in my Dart I aligned it mostly to the steeringwheel, which ment I had to make 4 new holes in the floors.
Don't forget to reinforce the floor where the new holes are drilled either. You really need to firm up the metal in those places.