Converting to different seats

Something that helps stock seats immensely is to hog ringing in extra springs.

Old furniture from craigslist makes for good donor springs. They are the same layout and gauge as these cars have. I've used them to replace broken ones, too.

If they need bent in any way, if you just use a propane torch, they bend on the hot spot easy.

I put a couple of extra springs going horizontally on both seat areas as well as the outer edges, longitudinally, where getting in and out of the car wears them down. The Scamp is super comfy, now. It felt terrible with sagged and broken springs, but they really do come back to life with some replacement springs from old furniture.

I used scrap foam to fill in low spots and hit it with contact cement and just used a grinder to shave it to shape, with a thin layer of sheet foam over the top. The only money I had in redoing the seat was for the upholstery, itself. If you get a junker chair, it usually has enough springs and foam to fix an old seat.