I think it will work out fine by not splitting the cases. So, now you don't have to pull the engine. It's all do-able in the frame. Pull the tanks, carbs, airbox and then clean, clean, clean. Wrap plastic sheeting around the frame above the engine to keep dust and dirt from dropping in to those spaces.
Adds to the part list:
Oil pressure sending unit, very common for these to leak, they are cheap. Good chance this is your leak and not a base gasket.
"Dad, can I get a motorcycle when I grow up?"
"Son, you can't do both"