I might do that, order some circuit boards.

The controller has minimal parts: 4 resistors, 2 diodes, 1 uln2003a and a metric crapload of wires.

I worked on software some last night. None of the thermistor libraries I found work with 2 thermistors which means I'll probably need to write my own code. Rpm should be pretty easy, count 4 or 5 revolutions and convert the elapsed time to RPM.

Controlling the air pump will definitely be pretty easy and I already can turn it on and off from my transmitter.

Adding an acceleration pump is a bit more complicated. Since we tune our mixture curve at static rpm, the extra fuel needed to accelerate the propeller to a new rpm is the increase in rotational energy: I x omega squared. Omega is the angular velocity and I is the moment of inertia. If we know the specific rpm vs throttle value we can create a rpm/throttle position table and use that to calculate the rotational energy going from one throttle position to another throttle position. Since we know the throttle position (since it comes on the sbus data stream, we know how much extra fuel to include. The only unknown here is the moment of inertia but we can just use a channel to provide that constant and tune it for the snappiest acceleration.