It caused the background graphics to just show up as solid colour blocks.
A big thank you goes out to Caius for not only making a modern day replacement for the custom but also for selling me one of his spare pcbs.
The KN6034201 reproduction pcb populated and ready to be fitted.
All graphics are now 100%, the only issue remaining is that there is no sound. This turned out to be a bad 6803 cpu, I confirmed this by swapping it into my other Kung Fu Master board. The 6803 cpu seems to be pretty rare at least when it comes to video games, they were more common in pinball machines so I didn't have any on hand.
I ended up ordering some from utsource (who I don't recommend) but they were very cheap so I ordered a few, this was lucky as the first one I tried was DOA. The next one I tried worked and the sound was fully restored.
Repair complete, thanks again Caius for making this repair possible.