340 actual horsepower

This is the article you probably saw. 1970 340 High Performance Mill Dyno - Mopar Muscle Magazine

It originally showed up in Mopar Muscle Magazine. I followed the build almost exactly.My 340 was a '69 date coded 340 for 1970. And it had J heads. Same as the X heads. My dyno results ended up being 410hp/412tQ. But I used Comp Cams Super Roller Rocker assembly, TTI headers and MSD's Billet all in one distributor.