In a 1955 issue of Hot Rod Magazine, they did an article on McGurk's dyno test of a 261 in various stage of tune -- stock, twin carbs, triple carbs, Corvette dual exhaust, milled head, hot cam, hotter cam, etc. Running a dyno test after each change.
After a point -- that being two carbs, dual exhaust, a cam slightly hotter than a 55 261, and increased compression -- they determined that for a streetable engine in a pickup, less is more. If you wanted more, bore it an eighth. In that guise, it put out more HP than a stock 265 and considerably more torque at usable RPM, around 2500. The wilder versions put out as much as 176 HP at 4800 RPM and were nasty to drive in town.
Look up the article. It's very enlightening.
