[Rich Biebel]

There was no factoring back then. Factory HP ratings stood and shipping weights as listed in the guide book. No driver weight was added. A car was weighed by itself and had to have 5 gals of gas in it. That was very specific and it cost us a record once. Pretty silly since the driver weighed 200 lbs.
The man who had the ultimate say on all of it was Farmer Dismuke. What he said was final. He could change a HP rating I believe. You have to keep in mind stock back then was not "Stock". Aftermarket pistons and rings other than stock were allowed. Cams were definitely not stock. New cars cost a lot of $$$ and the old cars were much more readily available, cheaper and proven combos. New cars were run by people with dealership connections or maybe factory support. And any new car/engine combo was a bit of a risk to see how fast it could run. For instance......the 1969 350/255 Chevy was not real popular at first until others showed how good it could run. The lower compression ratio made people hesitant to run one.The class guide book was huge....and cost some $$. People used to sit and dig thru it looking for good looking combinations. They still do! 2 books. Class guide and engine blueprint specs. All available now right here thanks to Dwight.