6-71 vs. 8-71

Yeah, I guess the main reason I ask is that I've seen SB Mopar kits with either size. The large majority of kits I've seen are the 6-71, but I have run across a few 8-71 kits. I guess a better question might be is anyone running an 8-71 on their SB. The kits I'm looking at are from Dyer's Blowers, they seem to have some of the best pricing I've seen for a full kit and they are also one of the few I've seen that have an 8-71 kit for a SB.