I do think you are right . But I have a set of #601 heads with new S/S valves . And screw in studs with guide plales . With the Z28 springs . I am about to start porting them out. Pockets and ports . They are going on a 355 with the 8.5 C.R pistons . The engine should have around 9.75 to 1 with these 55 to 58cc heads . The cam that I am using is a Elgin hyd 216/228 dur at 0.50 and 453in 480exh lift . I still am not sure what intake I will run . I do like the Weiand steath . COOL !