As an retired engineer I see 2 problems here, the main one being that the emerg lub system can't be tested on start up. The emerg lub system in the S61 took oil from a low point in the sump of the gear box, this low point was was part of a new sump that was part of the mod, I forget the amount of oil in it that could not be drawn on by the normal pump. The point is that it could be tested before flight. The 225 system can't as it uses glycol. To my mind the best fix (after fixing the shaft) would be to have a lub system that uses the same oil as the MGB so it can be tested.
The secondly the shaft hours might not be the same as the MGB. Some components, in the MGB, have longer ultimate hour than the MGB overhaul life. So the main shaft might be on it's second trip after O/H. I don't have a MM so I don't know the hours the shaft can do and though the MGB hours are said to be low nothing says the shaft is.