My goal is to essentially do the same thing that John from John's Arcade did in this video, except I'm just going to use Player 1 and 2 start buttons as Fire/Jump:
He used an adapter from Lizard Lick (no longer in business) to connect the Ms Pacman harness to a Jamma adapter and then connected that to a Jpac.
Whenever I search for it I just keep seeing lots people discussing the one from Lizard Lick or from Jammaboards.com (which is also apparently no longer in business).
Is there one out there that is known to be reliable and easy to install?