Got it all back together and it works good. In case anyone else runs into this situation I figured I would share my new knowledge after a little experimenting. I helped my friend change the rear brakes on his truck (disc brakes) and kept the old pads which still had some life left. I found out you can cut brake material off of the steel holder really easily with a metal cutoff wheel on a grinder. NOTE: If you do this, make sure you protect yourself. The grinder wheel worked fine but it creates A LOT of brake dust; I did this with a lot of ventiation, respirator, and goggles. I don't know what is in modern brake linings but I don't want anyone trying this becuase I said it worked okay and breathing in a bunch of brake dust; just use common sense and safety.
Anyway, once I got some pieces of the material separated I drilled the rivets to remove the old Jacobsen pads from the mounts and cut the new brake material to the same shape with the grinder. The material also drills really well so I marked the points where the rivet holes are on the mount drilled some holes to counter-sink some little machine screws into; put the head down inside the pad material. I also got some 3500 psi automotive epoxy that I put on the back before I screwed them on to also help bond them to the mount. Used it to mow a few times and it seems to be working okay so far. Figured I would pass this along in case anyone needs to create pads for their old tractor. Best part is that if you can find an old set of car brake pads this is basically free; just cost me a few hours and a few dollars worth of epoxy and screws.