I have all 3 games in Space Duel cabs right now.
To run Grav in the SD, swap the boards, and add a simple plug-in molex wiring adapter to play Grav on the player-1 controls on a SD cp. If you install a Grav cp on an SD cab, it still has to be re-wired to suit.
Be aware that a BW board is just a Grav board with different eprom images. They are otherwise identical. They are NOT the same as an SD board and SD boards cannot be converted to a Grav/BW board.
To play BW on a SD cab, you have to swap the boards and the CP's. An original BW cp has to be rewired to suit the SD harness. This can be done by simple rearranging the original molex pins so that it doesn't need a separate adapter.
I use the molex adapter to play Grav on one of my SD cabs so that I don't have to change the cp.
I have a dedicated SD cab for my BW (yes, it's that fun!) with a restored BW cp that is properly rewired for the SD harness so that it plugs in directly.