ST205, could I change pistons in situ? Options

[Riikan]

I'm planning change the head gasket & studs on next holiday, want take this chance also to press some arp conrod bolts / check condition of bearings.

Currently not enough space to drop another engine. All car I previously worked on could change pistons from under car no problem, but the Celica seems pretty cramped at bottom. Wonder do I have enough clearance to remove the : upper half oil pan, retrieve piston #4 , while the center beam still there?

Is the oil pan tricky to remove?

Thanks for any input!