There are several 914 savannahs here in Australia..they seem to go well but surprisingly not as quick as you think due to the sav being a bit of a drag bucket.
From the AP setups I have seen the roll servo is mounted on the flaperon mixer and the control arm from the servo goes to one of the belcranks on the end. The main stick for elevator the servo is mounted at the connection belcrank point on the elevator