If you are talking about the CompCams Magnum 280 which is .480 lift and 230 degrees duration @ .050, that is way too big. I run that cam in my 383, and I would not want anything bigger for the street. Call CompCams or Crane's tech line, and ask for a recommendation. Have all your specs in front of you. I think you will find that they will put you in the range 37 Chevy is talking about.