9in axle length

Going to to cut down a 9in to go under my 69dart. Using the wheel and tire combo 325/50 on a 10.5 wheel with 4.77bs the total width of the rear end will be 50.5inches measured. Axle flange to axle flange is 50" the extra .5 will come from the .25 thick rotor hats. I will be using 2.81 Lamb/Symmetrical housing ends. With the correct mopar pinion offset(1.1875) i am coming up with 25.375 passenger and 23.5 driver axle lengths and 44.375 total housing width. Does this sound correct?