7 1/4 to 8 3/4 swap question about driveshaft length

My documentation does not show any Mopar 727 transmissions with a 7 1/4 rear end. The documentation shows a 70 340 Dart with 727 and 8 3/4 rear has driveshaft length of 47.99".
This should be used as reference ONLY! As everybody else said " you should measure and do as your driveshaft shop tells you". This should give you a ballpark idea of the right length, hopefully.