Dart driveshaft needed. Any info would help

Putting a '74 motor up to a 63 PB 904 trans, requires a '74 flexplate and an adapter bushing for the end of the crank. (I have the bushing available for $20 shipped). I would recomment up grading your driveshaft. See link.
http://www.earlycuda.org/tech/ujoint.htm