The Star Rider CPU PCB that I borrowed does not work. It appears to have been partially destroyed by battery acid corrosion.
I've made a few attempts to borrow another PCB but these are going nowhere or else proceeding very slowly.
So... the next solution is to... MAKE A NEW ONE!
Uses FPGA to do most of the logic, but I am still using a real 6809E cpu just to save time (less debugging). Couldn't fit all of the EPROMs on the FPGA so still need to put two 2764s on the board. The rest of it is just ICs to make it safe to talk between 5V legacy ICs and 3.3V FPGA. Also shrunk down the control panel connectors to smaller headers and will make adapters if I get that far :)
Board will probably cost over $100 to make at this huge size. Hopefully I can shrink it down once I start routing the wires.
PS - if anyone has a working star rider CPU PCB (and VGG PCB) and wants to ship it to me, that would only help me.