From the photos, I would guess that it was way too tight, and never adjusted to the proper clearance. (This thread should serve as a warning to anyone who doesn't think they need to adjust their valves, this is why you do it.)
Unless the engine has way over 100,000 miles, I would just get another (used) exhaust valve, lap it and put everything back together. I seriously doubt that the guides and seals were damaged by a leaking exhaust valve, so unless I had a bunch of cash I needed to get rid of, I'd just replace the bad part.
Of course, I would be checking the other valves for damage, and replace any that were bad, but I'll bet this is the only one since I think you said the compression in the other two cylinders was still good. The only other parts you will need are a head gasket and some shims for the valve adjustment. (I'll bet all of the other five are tight as well. Did you check them before you pulled the head?)