B&D retracts are about 1960+ vintage and are no longer made. The only set I have is in imaculate condition thus I using on my Super Chaos, prior they were on my former MK Arrow (sob, sob).
Getting control valve should not be a problem and springairs should not be a problem.

I had to hollow out the thicker block I installed quiter a bit in order to clear the steering cable and let the standoff clear the surrounding areas.

Crashlander.