Mopar muscle did a rear disk conversion on a '73 Dart Sport and checked the stopping distances between the rear drums and rear disks from 60-0. Their result was that from 60 mph factory disks up front and factory drums in the back the car took 133 feet, 6 inches to stop. After the rear disk conversion, the stoping distance improved to 122 feet 4 inches.
The online article is a total mess now, probably something with being converted over or moved to Hot Rod when MM was bought out. The final distance used to be a caption on the second to last picture, but I don't see the captions popping up anymore. The hardcopy article is easier to follow, but that's the way it goes.
Rear Disc Brakes - All Bound Up - Mopar Muscle Magazine
Now, there are other differences here no doubt, tire compound, road surfaces, driver input etc all make a big difference which makes comparing two different "at home" kind of tests hard to do. But the numbers you're getting are A LOT better than what Mopar Muscle got. And their stock numbers are pretty close to the factory published numbers I've seen. I'll have to look it up but somewhere I saw a drive test article from back in the '70's on a Demon that put the stopping distance around 125 ft if I remember correctly. I'll try to find it.
***Edit***
Here's a Road Test Report on a '71 340 Demon. Not the one I was looking for, as this is a drum/drum car. Neat stuff though. The stopping distances were absolutely abysmal, for anyone that says drum/drum is ok on the street today. The Road Test guys said they expected a 60-0 of 155 to 165 feet. What they actually got was a stopping distance of 169 ft, on a 3,250 lb car with E70's. That was their "best" distance, not an average of their results but a one off. Their Demon had 10" drums and a power booster. They did say their road surface wasn't ideal, but dang.
Vintage Road Test: 1971 Dodge Demon 340 – Road Test Magazine Takes A Real Devil For A Spin
