Rear Seat Padding

Looking for advice on what type of materials I should put under my new seat covers. I have a 67 XR7 with the dark ivy gold interior. I have pulled apart the rear seats and quite honestly it doesn’t look that difficult to install new material and the covers. The original cotton padding material seems it’s just lost its cushion over the years. Who has redone their seats and what material did you go back in with. I watched a video from legendary auto interiors redoing a rear seat for an older mopar and they used a high density foam for the bottom and a factory style roll of cotton for the back padding. They offer a nice padding kit I’ve been considering getting. Any input? The front seats I’m convinced I’ll have a shop do those since no one seems to make an exact replacement foam for the XR7.