How fast can a stock leaf rearend be?

I've been best of a 6.64 1/8 and 10.46 with a 1.46 60' with nothing more than Mopar SS springs, no snubber no drag shocks and All steel no lightening of the car. Also that was running a 10.5 slick on a 7" inch rim.

I've seen some of you guys mentioning tire sizes like 10" or 10.5" wide slicks on pictures of Dusters. Do you know the largest width of rear tire that fits under a 71 Duster with no susp mods?
Sorry, didn't mean to hijack this thread !!! I will put this on a separate post.