Freds
Might just make it,Been a long time But.........
Remember there is just so much room between the firewall/tranny hump AND the fixed position crossmember that was the Original rear mount location for the standard shift trans.
Seem to remember you could sneek a 3speed and engine in there but a 4speed hung to low in the "belly" to leave it on for removal or installation as a pair.
The pan on a powerglide might make it over that c member but I,m leaning on NO,sorry to say.
Its gotta go in AFTER the engine is in,OR before,and stab the motor on it.
Good Luck and Regards