Are you sure the monitors are running composite? I did a bowling alley project a couple years ago and looked at replacing the old CRT monitors. The problem wass it was some proprietary connector that Brunswick had to try to keep their customers locked in. In the end, the owner decided to leave the monitors until they die.

But someeoe here did turn me onto this company
[Link: evolutionscoring.com]

But the best thing is to walk away if they arent willing to spend some money and do this right.