It’s not a complicated conversion. You need the patched files, then you need to burn the rest of the eproms. As for the protection chip, you’ll need a diode. Last step is to configure the jumpers as you’ll use eproms instead of maskroms.
As a follow up, my friend bought another Multi kit (this one is V2). I swapped the main and interconnect pcb with the new ones and it works perfectly. The sprite issue seems to be in the multi’s main pcb. He asked me if it is possible to send it for repair ?