I ordered a set of comp 1.72 roller rockers 249-RPS302r and it says it requires machine work to use them on these heads but i don't have any clue what machine work it may need. I have access to a milling machine and other stuff I just don't know what I need to do.I also have a comp cam intake lift .507 exhaust lift .512 and I was curious if anyone knows if I'll run into any clearance issues with that cam and 1.72 rockers. The cam claims no valve train modifications are needed.