The original G-version 617 oil pan is a very large cast-aluminum unit that does not have a separate sump & gasket. This pan does retain the lower portion of the RMS. I have not replaced a 617 rear main, and I have not pulled the G-version oil pan, but most people live with a drip unless/until it becomes a stream. I doubt there is enough room to fully remove the oil pan.
If you're going to pull the engine (about 2-3 hrs of work) you might consider just swapping in a non-leaky 617 turbo engine in it's place. That and a Dieselmeken fuel pump will give you 200 HP and a huge boost to your investment.