Here is an interesting article explaining gross vs. net horsepower and how the classic muscle cars compare with the modern ones. https://www.hagerty.com/articles-videos/articles/2013/08/13/horsepower
The Hagerty article's horsepower comparison is based on 1/4 mile times. Here is a fairly accurate calculator, based on horsepower-to-weight, that will provide you with similar 1/4 mile results. https://robrobinette.com/et.htm
This is the muddiest issue anyone talks about.....at least when trying to compare "old Muscle" to "new". It's true that many of the old cars weren't near what legend says about them.......but some really were a lot more than advertised and really still stand up pretty well to their modern clone attempts. It's all about power levels though.........the Idea of POWERFUL still stands up in the best offerings.......but the comparison to modern car tech ends when you consider these were pretty much race only engines that we're pretty miserable as daily drivers. Absolutely HORRIBLE MPG and enough crap coming out of the tail pipes to blot out the sun on a nice day in Southern California in the late 60s and early 1970s. The power was there though in some of the offerings. This is no joke. In this class of drag racing "STOCK" means "Stock".....these cars can be "optimized" to run their best with any gear ratio offered from the factory back in the day......but they do have to run full exhaust, manifolds (no headers) and carbs and internals have to be "stock"......the only concession to "modern" allowed are tires.
Within a few minutes of each other saw a 69 boss 302 obviously hotrodded could hear it idle from 500 feet away had the rough idle of a after market cam then saw a new camaro zl1 if I didn't know whatyou it was you would assume the mustang would've blown it away.And I have dodge magnum srt pushing about 509 horses just live the look of horrors wondering how I'm keeping up with them in my soccer mom's car Sent from my P008 using Tapatalk
