Are you still looking for an I/O board?
What you're really asking for is a Slot I/O Board, not a Video I/O Board. 2 totally different boards. Even though Jackpot Party has a video component, it's still a reel game and a Video I/O board would not work in it. It does not contain the components to drive the reels. There are multiple versions of the Slot I/O board, but they are generally all compatible.
Is this about the Fail LED being lit? If so, it's not necessarily the I/O board at fault. The power supply is the usual culprit, but a problem on the CPU board or backplane could also trigger that LED to light/flicker. The user manual isn't really helpful when it comes to these errors, it just basically tells you to replace everything with a new one and try again, which is obviously just about impossible today.
I recently went to change a long time working game with another previously known working game on a separate CPU board. After running a clear, the new (previously working) board did not take. It just triggered the Fail LED, no bong, no init. I reseated everything, replaced the battery, but still remained with the Fail LED. Swapped back in the original board and it was fine. Strange it did not follow the 2nd part of the clear routine, it just booted like nothing ever changed. So something is going on with that CPU, I'm going to continue troubleshooting.
Point is, the Fail LED is just saying 'something' failed very early during the boot process. Could be the I/O, could be the CPU board, could be anything. It's not just a self-diag for the actual I/O board itself. So don't be tunnel-visioned on just that piece of the problem, explore all the components for issues.