Driveshaft length. Is there a solid answer?

So I'm planning to do a slant swap on my 73 Duster. I have everything for the swap now but the driveshaft. My good friend and I want to do the transplant fairly soon. I'd rather not be down for weeks waiting on the driveshaft. Since everything is 100% factory, I should be able to just have a standard DS built. However I've found 3 charts online on Mopar forums and they all give a different length. Is there a factual number ??? 360 LA, 833, 8 3/4 rear.