Dart driveshaft needed. Any info would help

Yeah, the motor is out of a 74 scamp. Would it be smarter to just have the push button rebuilt? The motor is all balanced, has a comp cam, valve job, 4 barrel and split headers. Then an 8 3/4 out of a barracuda big block car I believe. I think it has 3.55's. I put the springs that came with the rearend back there too. Hoping to be able to smoke those 14" tires a little bit but we will see. haha. Hopefully I can afford to put a 408 in someday or maybe a late model Hemi. Always want more. Part of the hobby I guess.