Konami X-men 2Player to 4 or 6 player

[hyp36rmax]

information:
the 6P - GX065 - PWB352532B pcb can NOT converted into a 2 or 4 player version
just tried several times...........

The 2 player PCB with a ROM swap can do 4 players.
The 4 player PCB with a ROM swap can do 6 players.
The 6 player PCB (GX065) can only do 6 players (thanks for the info @Astro X)
The 2 player PCB cannot do 6 players.

Can you still connect (GX05) to a supergun and play two players with the other player slots unoccupied on a single screen? You'll still see P3, P4, P5, P6 on the screen?