drive shaft advice

[zicc1835]

I purchased this one piece drive shaft from a board member came out of a inl6 with a 350. I dropped engine trans in the frame this weekend. The shaft fits yoke catches about 1.5 of the slpined shaft so from my yellow mark on the yoke its a 700r 4 it goes into the tale shaft 1.5 inches leaves about an inch of shiny shaft exposed .....do i need more than that i would hate to have to extend this shaft is there enough on the splined taleshaft ?