Wow, what a pain!
I've had gasket failure happen, mostly with 3spd BW Auto trans pans.
I usually spray cork gaskets with Hylomar sealant,
but found if I coat it too much without drying properly first, the gasket goes soft and breaks
My factory XB service manual says 7-9ftlb for the smaller pan bolts,
and 11-13ftlb for the larger ones at the end.