I run a Sifton 412 with about 60+ overlap in a 1952 74" motor. It comes on a bit late. Upon further research I've calculated my gearing, compression, carb diameter and exhaust length. This cam's specifications should improve throttle response, torque and overall performance at a lower engine rpm. But, when I opened the box and looked at the lobes? Huh? That's different. Looks like a mini version of a Leineweber with those tall ramps and flat tops.