Dart driveshaft needed. Any info would help

Hey there, have a 63 dart gt. Have a mildly built /6 in it and an 8 3/4 rearend. I thought about putting a 727 I have that was previously built but its out of an 85 pickup. Does that matter at all? It currently has a pushbutton trans that is in pretty rough shape so want to replace it. It has a trunion style driveshaft that doesnt fit now that I put the 8 3/4 in back. So can I put the 727 out of the pickup and is there a stock driveshaft that will fit under the car? I have a 727 out of a 74 scamp I could also use if the truck trans wont. Any info would be greatly appreciated.