CG, you’ve gotten some great advice!
One other thought. Some cats have very limited tolerance for petting at all, and some also have very limited areas where they will tolerate being petted.
One of my outdoor ferals, Cammie, doesn’t like being petted anywhere behind her shoulder blades. She can handle having her jaw stroked, and she will headbutt my hand. But she likes being scratched gently, not vigorously. Her tail is stumpy and appears it was amputated, and the vet also found a few bone chips near one of her hip joints; we figure she may have been involved in a car accident at some point and may have lasting damage or trauma from that event. In this case, it would make perfect sense that she doesn’t like to be petted where it hurts (or at least where it doesn’t feel good).
Another of my outdoor ferals is a neutered male, Bert. He will jump up into my lap if I sit down, and he follows me all over the yard when I’m outside. He’s very territorial and aggressive about defending his location. He tolerates some chin scritching, and some minor scritching between the shoulder blades, but that’s about it. He doesn’t headbutt, and he really doesn’t like being petted along his back or chest. I might get one hand lightly down his back once, before he turns around and tries to swipe at me. If I don’t pay heed to his clear warning to stop, and insist on petting him again, he will definitely turn around and chomp on my hand hard enough to make his message clear.
Regarding your cat, you will want to watch very carefully for signs that he’s not enjoying being petted, or that he’s getting overstimulated. Watch his ears carefully; when they start rotating to anything other than a front and center position, he may not be happy. Watch the skin on his back; if it ripples or twitches, it usually means discomfort. Watch his tail, too; if the tip starts waggling back and forth with more animation, or if he starts whipping his entire tail, stop.
This is a good bit on cat body language and communication; might help.
http://www.messybeast.com/cat_talk2.htm
Good luck!