if you really wanna "blank" rig it, you can take a small grinder and hack saw and cut some notches in the upper oil pan. If you do that, you can line up the big space in the teeth enough to where its possible to slide if off without pulling the upper oil pan. Then when you put the front cover back on, just make sure theres lots of the GM RTV goop filling in the notches.
I did that because I needed to swap reluctor wheels when I put my LBZ shortblock in. So rather than having to pull both pans, flywheel and rear cover.....I spent 15 minutes with a hacksaw and swapped them out like that. No leaks or anything...
ben