I went ahead and threw a 1uf@ 50V in there. It is in the sound section, so I hope it just wouldn't be as loud as normal if it was wrong. It was also the lowest value I could find. It has not exploded after a couple of minutes after power up.
It all seems to work, the game boots, and plays with full sound. I had never played it before. I am not sure if the game has a good reputation or not, so I hope it was worth it.
My hand built Irem to JAMMA adapter from parts, took me a few hours: