There was a guy named Major Cooksey (spelling might be off) who prepped Top Fuel 8.75's right up until the tire shake issues forced everybody to go to the Ford 9 inch. This was around 1974 or so. Car Craft did a feature on his rears sometime in the 72-73 timeframe. Can't find the article myself right now, but I remember it having some seriously good info on setting up the 8.75 to live behind 2000 horsepower. I know that Garlits for sure, was one of his customers.
The rears used back then were all based around factory castings, and up until 72 were almost all open, using stock spider gears and such. Builders would shim the spiders tight and the power was evenly distributed, but there was that little measure of slip that would absorb most of the shock that would typically kill the case when one tire would get loose and suddenly grab.
The technology was fine at 2000 horsepower and 1400 pounds. As the weight goes up, the amount of power you can pass through the rear goes down, obviously. But, at 3000 pounds, there's no reason on earth a properly prepped 8.75 won't hold 750 horsepower with an automatic and no brake.
The most extreme application of 8.75 I can think of was the Mr. Norms 65 Coronet. Approximately 1200 horsepower at 2700 pounds with best laps down in the 8.60 range.
