Not all system 11 games are created equal. You need a game that uses an interconnect board in the backbox, so you will have a compatible wiring harness. Big guns has a funny cabinet and doesn't have an interconnect, so probably not the best. The interconnect boards are specific to their respective game.

Jokerz is probably the best donor for a bad cats swap. Both the lamp and switch matrix will be correct, but you will have to change the pinout for the solenoid power. Jokerz uses the same display as bad cats, but it has a different sound board. Doing the swap isn't as plug and play as you might think.

IMG_20210502_063722576.jpg

You need the interconnect board. It is specific to bad cats.

https://www.marcospecialties.com/pinball-parts/D-12313-575

Jokerz is a fun game, I put 600 plays on it before I converted it. I also kept all the parts because the conversion is reversable. If someone were to make me a SoF cabinet, for example....

Me-ouch!