Throwing a multicart into a classic cabinet automatically disqualifies it as a restoration, and puts it into conversion territory.
This should probably be moved to Project Announcements.
That being said, most of the games in that multicart use more than 1 button. Are you planning on putting holes into the original panel?
Also, I vaguely remember this cart doesn’t like -5v, how are going to handle that? Are you going to build a Gyruss to JAMMA harness and just not include the -5 in the conversion?
Gyruss is a classic, and the cabinet is a wonderful piece of history. It was the first arcade game to host stereo sound output, which was merited by the awesome classical soundtrack. I remember trying Gyruss on those Game Elf carts and the sound being off in a few games including Gyruss.
Personally I’d keep this as a straight restore, but it’s your stuff - you do you.