I wanted to offer my solution just in case people want another alternative to this problem.
My dead yakuza board (non usb) as shown here in my pm5 ul frame: RIP
Now has a used Pm8 board as shown here installed:
Turned off first shot setting for spool guns (dip switch 1 down) and turned the dwell down from the board's stock setting of 18 to 10. Bloodsplatter tarantula shooting laser ropes once again!!! No frame mods required. (However, last pic shows the board hole is too small for the yakuza screw to hold it in place, but not a big deal the ul frame is so small the board is not moving anywhere with battery in place).
Big thanks to Tim and Sol for finding me this board and hooking up the elusive back plate with the correct buttons.