I can tell you that finding those arms is gonna be tough....it's one of those "impossible to find" NOS items. The best bet is to find another complete top and just take the hatch and mounting parts from it.
To my knowledge, NOBODY makes a replacement hatch....or any of the latching hardware. If you've got restorable parts you will probably need to use them for now......and keep your eyes open for "better used parts" that you can swap in when you find them.
.....It's all part of the "fun" of owning a 30-year old truck! /forums/images/icons/smile.gif