Which yoke??

I'm going to the pick-n-pull yard tomorrow to find a trans. yoke for my 727 big block 66 dart build. I'm trying to find the bigger u-joint. How do I tell if the yoke is the bigger one or not? What measurement do I need. They only made two right? 7260 and 7290? Will the 729 be sufficiant in a high 10 second street/stripper? Do all 727's have the larger u-joint? What about pick-ups? Do all 727's have the same spline count?