I have an old Gov-N-Air system from WDP, and the tank threads are very different from my Geddon tank, so compatibility might be an issue. I know there were two standards at one time, the metric tanks, and the fractional, but who knows, WDP may have switched over, but I doubt it.
E-mail WDP and ask them what the threads on the AIR reg are, then e-mail the tank producer with the serial #, and ask them what the tanks threads are.