Rookie driveshaft question

[polevault1977]

I have a short 70 frame with 350 on front towers with a 700r4 behind it. I did not have a drive shaft with the pile of parts that I started out with. I went to the boneyard a got a drive shaft out of a late 80 swb pu that had a 700r4 in it. I knew to would have to shorten the shaft, but forgot about the pinion yoke being different. Should I get an older drive shaft and shorten it or can i use the one i have by letting them weld a different yolk to the rear that will match the 71 rearend that i have with the external snap rings? Also does anyone have the same set-up that i do, if so what was your center-to-center measurement? Any help appreciated. Learning as I go!!! Danny