you do mention that this upgrade is a must.This is a perfect example of why the button remapping chip is such an essential upgrade for a project like this. The way buttons are mapped for some consoles just do not make any sense on an arcade control panel.
Honestly, I think this feature should be in the default purchase and just embedded in the price. I don’t know why anyone would choose not to get this upgrade. Not having a remapping ability for a lot of console games would be just hell.