sorry, i haven't looked through the whole thread but a couple of questions about your turbo setup that could help, potentially.
Does the
oil drain have enough fall into the sump? if not then you can use a diff
oil/scavenge pump to pump it into the cam covers ,
oil filler cap.
Switched from ign acc on and with a timer for 5 to ten seconds after switching off can draw remaining oil from the turbo (also does away with any need for a turbo timer)
Are you running a oil filter inline into the turbo, to suit the feed line? these as well as a low pressure (2psi) check valve can stop oil draining into the turbo once the engine is switched off, assuming you have a length of oil line falling into the turbo.
hopefully something i suggested can keep you on track to over 400kw atw.
see you on the other side....
