I have an empty Space Invaders which I put a 48-in-1 board in. I made a new CP with joystick and buttons. I was careful to keep the harness and insides intact in case some one wanted to fully restore it in the future. Unfortunately, I don't have room for it in my collection... so it will be lent to a friend soon.
Trickiest part was to install the monitor. Had to remove it from the frame and install the bare tube in the cabinet, then mount the chassis to a piece of plywood and reconnect to the tube. Somewhat frustrating, but I wanted to be able to use the half-mirrored glass and the original black light and background.