drive line

the 65 barracuda now has a 727 and has 8.75 in it. I put the yoke in transmission all the way back it out around an inch, there is weight is on suspension and I took measurement from center to center and got a measurement of 46 inches, does this sound like the right process to get length of driveshaft? side note is there a shorter transmission mount out there i used the 65 rubber mount and the tail shaft hits the bump stop in the tunnel.
I have that setup in a '66 Barracuda, and mine is 46" center to center too, so, you should be good.