My bore is 4.280, it’s a world iron block, it is notched at the top already but not sure if it’s enough. I don’t have the Indy heads yet. I do have a buddy with the stage 5 millennium heads and those 2.400 intake valves hit either the block or the piston. I did try it with checker springs. The Indy heads I’m thinking of come with Norris rocker arms, how good are those rockers? Thanks