My experience was brief, but I'd let the thing go at about 5000, shift at 7000 - 7500. 4.10 gear, pretty much stock weight, 3870 with me in the car @ about 160lbs and 1/2 tank of gas. On the street I could spin them out of the hole but not between gears.
I still have them, mounted on Centerlines, and fronts too, if you're interested.
Ernie was one of the true gentlemen of the sport.