This didn't quite work out the way I had planned. The seat pan for the Saddlemen seat is made of plastic, which has apparently become quite brittle over the decades; the plastic surrounding one of the hinges just cracked the moment I applied pressure to one of the bolts. I had planned on selling the seat, so I didn't proceed with the other hinge or the lock catch out of fear of mangling the rest of the seat pan. It also already had a fairly substantial crack in it when I bought the bike.
So, is the seat pan toast? Or is it an item the an interested party would be willing to repair or restore? (JB Weld or something? I dunno.) Or should I just tear the rest of the parts I need off of the seat pan and sell the seat cover and foam?
I'll also have to hacksaw the heads off of the bolts on the seat hinges. Here's the reason why:

Those things will not budge!