Not only does 602 refer to the last three of the part# 88958602, not the C.I.D. but it has a cast crank, dished 4 valve relief pistons, 3/8 pressed in rocker studs, stamp steel rockers, and Vortec heads with 1.94/1.5 valves. 9.01 to 1 compression. The only thing that would need to be changed is the intake, as they are aluminum. Now a 604 is illegal as it has roller cam, aluminum heads, and aluminum roller rockers... Just an FYI. http://scottsautomachine.com/crate_engines