I think that you are right about different kinds of biting. You will have to be aware of any and all body language that Henry uses along with, and shortly prior to biting. It sounds as if he is easily over-stimulated with affection (think "marrying a middle-aged bachelor "- like I did- a 50 year old!
) and probably isn't used to a lot of one-on-one. For kitties that don't like too much petting, I try to give just a little affection, then give them their space BEFORE they demand it. Another thing is that maybe Henry has a chronic sore or sensitive spot - my cat Cinders was rescued after months of living in a rest area & her biting alerted me to a sore right shoulder; a vet exam showed some scarring indicative of an untreated injury after being hit by a car or possibly kicked. My Persian-mix Miss Tobie was adopted from the shelter already declawed; she had been rescued by the police when they also arrested a husband who had beaten his wife so badly that the lady was hospitalized and the children taken into protective custody and animal control took the dog & cat, so she had several issues that led to her biting - adopted as an office cat (at first she was awesome)she would suddenly bite me, our secretary, tried to nip a client; I took her home & my grandson came over for a weekend visit -when she tried to bite him, he put his arm around her little cat shoulders & told her, "You don't have to bite anymore, Miss Tobie. This is a real home with a real family that loves you very much" and voila! she didn't bite ever again.
Now, Joey has suddenly started hissing & biting at JC (they were adopted at about 6wks. together, but from different litters) after over 1 yr., and if he's upset with JC, he's tried to nip me - I just hold him firmly & tell him to calm down, and as soon as he calms down, I put him down. But with JC, when he doesn't want to be brought back inside, He tried nipping for the first time the other day, so I put him down and told him that I wasn't petting him - he seemed to sense that & did every cute trick in the book do get me to give him attention, but I made him wait. Last night, he wanted to try to escape, I caught him & he swung his face around to nip, but I warned him, "Do you want to get ignored?" and he relaxed, so I immediately gave him "loves" and then spent alittle extra time pulling a rubber lizard on a string, to give him 1 on 1 playtime that also used up some of that "hunter's energy".
There seems to be so many kinds of biting. I'm sure that someone more knowledgeable will give you some better tips. You do have my sympathies - I love cuddly cats the best, and I think that deep inside, every cat has that potential, it's just that they have endured so many obstacles & developed so many defenses as a result, coupled with the fact that they can't verbalize what they need & want from us.
Bless you for taking in Henry into your family; best wishes for a close, happy relationship that brings you years of wonderful memories. Cheers, Susan