Eric,
I'm same height as you – 6'3" and manage with most 34" lengths which are usually available (but a 33" is no good, I push it to the limit;). You've go some long legs(or you where your pants really high). I've never even heard of pants being made a standard 38" in length – except at a specialty shop.
That being said, i typically like my hiking pants to be a bit shorter on me. Doesn't earn me any fashion awards, but it keeps the cuff from dragging.
Years ago, I cut the lower 6 inches of my pant leg and sewed on a waterproof section in an attempt to create a UL integrated gaiter – looked pretty bad and didn't work too well, but if you did that properly (not waterproof) and just added 4 inches to a 34" pant, it could look fairly decent. Just a thought.
Steve