Once 3.2 has been installed, will it be ok to start the engine with SV turned on and the back up battery connected, bearing in mind i don't have alternator switch to turn alternator off?
I believe that is the preferred way. SV is made to take the voltage dip during start but will reset if the voltage goes too low. The backup battery will keep SV on during start if that happens. You want it on to check the oil pressure after start.