You might be able to get the engine/trans assembly installed together if you take the top cover off the transmission, but it's much simpler to install the engine and bellhousing as a unit and then put the transmission in. An engine lift through an open door or a 4 X 4 timber across both window openings and a cable come-along makes it a simple job to lift it into place. Removing the crossmember was a huge mistake, as it allows the frame rails to spread out. The crossmember is a structural brace for the rear spring mounts.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!