SAAB 900 and VW Rabbit / Golf had air up configuration, the dist was on top of the air filter. This made sense since the dist was off engine.

Accel and decel are going to affect fuel mixture even for a short period of time. What are you wanting to gain by turning the fuel dist?

For a warm up regulator I'd probably use an adjustable fuel pressure regulator with a remote cable, this way you have easy adjustability. Given the car is limited use, cold starts could be accomplished by turning the knob X turns.