Okay I thought you were putting 73/74 E body seats in a 73/74 E body that had the wrong year seats.
You are putting E body seats in an A Body. I see the more clearly.
It will be easy to modify the seats to be left or right.
The tracks may be a different story.
I believe the difference in the seat tracks has more to do with mating the floor pan to the seat style.
Do you have A body seat tracks?
I have some Ebody Seat tracks in the basement and I can measure the mounting points tomorrow if that will help.