i had the exact same setup a few years ago with a ported and polished head. rods have to be modded but its not too expensive for a machine shop to do them, its a fun setup, granted the compression is a bit high for everyday driving and detonation is a big possibility, but its definitely doable if the tune is right. a big cam will probably cause some valve clearance issues with a thin headgasket, but with a oem layer,you should be fine. but i didnt put large cams in the ls head so hopefully some other people have experience putting some big crower cams in a high compression ls will have some input. i then did a vtec head conversion and i never had any issues and the car was even funner.