my seats in my 89 formula were suffering from fallen bolsters but the fabric is in great shape. so a friend had an extra pas seat hanging round so i took it off his hands.
i cut a lil off my dr side bolster and took the inner bolster off the pass seat and glued it on and used the donor seat cover to test fit while my seat covers were in the wash.
after doing the outer bolster i studied the inner bolster and slit the side, stuffed foam in it an trimmed it clean. test fitted it and both were just right. it was tighter than my pass seat which was pretty much perfect.
while i was in the seats i added more lower leg and back support and lower seat bolster support.
looks all stock still and feels like custom seats.