The only thing that might give a run for the HP 273 would be a HP 360 from 74-76 and it would have to have the 340 cam and valve springs. I also thought we were talking stock? Once you upgrade a 360 to the same level or higher, all the same goodies, the 360 should win. A lot of people discount the 273 but don't realize that 235 HP at 6,000 rpm will kill a 318 with 230 HP at 4,000 rpm. Same for a 360. They made 360's since 1971, mostly 2 barrels. A 5.9 Magnum with a cam and good intake and carb, should, but not a stocker in a truck. I've had or built everything except magnums, an RB, and a Hemi. I know what they all do and where their strengths and weaknesses lie. We all decide how far we are willing to go and how much time, money, and aggravation we are willing to put up with. Knowing what it takes to run and survive without breaking parts is big with me. I never had the luxury of a race car, I always had to drive my car the next week.