I actually have a cossie master cylinder mated to a pug pedal box from the original conversion but I have binned the abs although I believe you can still fire up the pressure accumulator so I could have a go at wiring that in to come on with the ignition although never liked the noise they make at start up and seemed to put a big battery drain in.

Thanks for the advice re the plenum, I wondered if there were better or worse areas in the plenum but I guess adding it where the other sensor holes are should be fine?