Been a busy week since return from EVO, but I should have a free morning on Saturday. Will hopefully have an answer for you guys then!
15 Pin D-Sub version is definitely the more elegant solution, so don’t feel too bad
What I mean by “monster” pads is the Neo Geo connectors on the supergun have large pins soldered to the PCB, which makes it easy on you. Also there should be large pins on the bottom of the supergun for that big screw terminal connector you wired your kick harness into. After cutting the appropriate traces, solder a wire from the bottom of B5 on that big screw terminal connector to Pin 10 on the Neo Geo connector (do that for both Player 1 and Player 2 connectors). If you wish to wire up Coin 1 and Coin 2 (it appears there is a button on the supergun for coin, so you may not care about this), solder a wire from JAMMA Pin 16 to Player 1 Neo Geo connector Pin 3 and solder a wire from JAMMA Pin “T” to Player 2 Neo Geo connector Pin 3.