1965 barracuda seat upholstery kit install difficulty
Standard rear benches are fairly Easy to do. Not sure about a folding bench back.
Bucket bottoms are easy as well.
My 73 bucket backs were difficult as they had listing wires in the front.
Those low backs look a lot easier.
Hog rings can be had a Tractor Supply. Hog ring pliers at Harbor Freight.
I used 2 pair of channel locks and a welding vise grip (with the wide jaws) to pull the material tight while I hog ringed it.