/6 to V-8 swap question

Looking to swap a 318 drive train from a 1974 4 door valiant into a 73 duster with a /6. I will be swapping motor, trans and rear all at the same time. Question is will the drive shaft be the correct length or can I reuse the duster /6 shaft?

If they are both 904s the driveshaft you have will work. You do know that the /6 K frame and the V8 k frame is different, right?