I was actually thinking of only using something like cinder blocks/jackstands/etc to hold the car AFTER the transmission was detached, so I could slide the transmission out (I'm assuming from the rear is easiest?). I'd never sit under a vehicle for hours without at least two of the wheels being firmly on the ground.

I'm just curious how high the car needs to get in order to clear the bellhousing + jack, and if jackstands go that high. Or maybe someone has a recommendation on how to get the car high enough when I don't have a car lift (I just have an ordinary 2-car garage).