The rubber transmission mount is a one piece "U" shaped item with molded in steel bushings. If you're going to drop the crossmember, you might as well replace the rubber mount, especially if you don't know the age of your old one. Since you only require one, it's only $39, not $78, for two, as you thought.
I have a Muncie with a Hurst Comp + in my 56. I couldn't get the two mounting bolts to go in the the Hurst adapter plate. The heads of the bolts werehitting the side of the tunnel , not letting me slide the shifter into position to start the bolts. After screwing around with it for a couple of days, I took a 1" dia hole saw and drilled two holes through the side of the ttransmission tunnel in line with the bolts and installed the two bolts from inside the passenger compartment.. Saved the two discs and glassed them back into the two holes when finished. The carpet covers the "Bubba" solution to my problem.