I put a 327 in my '49 way back in about 1985. I fabed boxing plates for the inside of the front frame rails & made tabs frmo there to the side mounts. I used an m21 4 spd with a mount from the rear crossmember to the tail shaft. I left the center crossmember in place, but the motor is not attached to it. I did move the steering box out about 1.5 in. This set up has worked great for many years.
Good luck.


1949 chev 3100 3 window. 350hp/327/m21 4 spd, 12 bolt rear, power brakes, 3" dropped axle from Sid's. Disc brakes next.