...One other ride that I almost forgot to mention that might be a problem is the Finding Nemo subs. That is a very tight, enclosed environment and those seats aren't very big with hardly no leg room in front. DB didn't go on it the last time we were at DL but I would imagine that it could be a problem.
The Nemo subs are very cramped as mentioned, but I think if you're on the very end, you get more room? Not sure if it would be enough... In a pinch one could also feasibly "intrude" into someone else in the party's space, I'd think.
(But if he doesn't like small spaces and/or doesn't love Nemo, I think it's fine to skip. Actually, if he hates small spaces but loves Nemo, he can see the "alternate viewing experience.")
I second that Space Mountain will be tough, I'm 6'4 and I have trouble getting in and out of that one. I'd recommend skipping Goofy's Sky School and Gadget's Go Coaster (won't be missing much with either) and maybe tell him not to put his hands ALL the way up on the Matterhorn. I'm sure if there is any danger of him really getting hurt the CMs would let him know.(I've never been told I'm too tall for a ride at Disneyland, but it had happened at 6 Flags.)