If memory serves.............
The oil Drain plug is where part of the oil pump pick up screen holder, so I don't think you are in any luck there.
I had an extra oil plug added to my 94 with a magnetic drain plug under the crank. The shop drilled a hole in the cases and then welded a threaded boss over the hole. I imagine the same could be done to mimic the later year bikes that have the separate drain plug next to the oil p/u screen holder plug.
Dale