I have dropped my transmission on my 93 NA. The engine is now supported by a harbor freight cross beam + ramey Z slinger (bolted to the middle of the intake plenum).
I would like to drop the oil pan.
If i unbolt the engine mounts and drop the lower subframe, will the engine stay perfectly balanced?
Has anyone tried this?

I would like to replace the rear main seal/retainer gasket/oil pan gaskets, before putting the tranny back on...

I would only lower the subframe a few inches. It does require disconnecting the steering rack from the steering column, and a few other lines, but it would still make the oil pan drop very simple.
I am removing the oil filter bracket anyways.

I can't really lift the engine much with the HF cross beam. Only about half an inch.

Any advice?

The Ramey Z slinger is well balanced. I've pulled my motor several time with it and the engine stays relatively the same position as it sits in the bay. You can tilt it manually a few degrees in any angle by hand when required.

I just tried it, and yes it is well balanced.
The engine did move back only about an inch when i lifted it off its mounts. That is with the flywheel removed. The headers are still on.
I rigged a couple of 2x4s and some straps to lift the front of the intake plenum. That brought the engine forward.
Overall, the Ramey Z and the 1000lb Harbor Freight Cross bar, were a good investment for this job.