The cross member under the rear main and bell housing shield will be in the way, making it difficult to put the seals in.
Of course putting the
oil pan back in (remember the stud holding the
oil pick up tube) is even more difficult than getting the
oil pan out.
Holding the oil pan gaskets and windage tray in place is also a pain.
Something to keep in mind is I have a forklift with a boom to pull engines. So pulling engines is very easy.
If I only had a cherry picker, I would leave the engine in.
However, if I did not have a lift, I would pull the engine.