Honda doesn't make seats other than the type that came with the bike. Your best bet, not cheap, would be either to contact a custom seat maker like Saddleman or Corbin or have an upholsterer who knows bike seats modify yours.
Mark Hart @ Hartco International is a tall guy himself, and I've been a big fan of their products since my first GL1000.
My most recent Hartco was for my 1500 (the blue bike in my avatar here) with a seating position about 3.5" taller and a little more than an inch rearward. Even with 35" arms you don't wanna be too far from the handlebars, that geometry changes rapidly as you adjust em (remember, youre moving up too!), and your lock-to-lock low speed manuvering can suffer...
As mentioned a good local upholstry shop may be a first stop. Replacing that OEM foam with something that on't compess so much can get you some height, and as Paul posts, moving the bucket a bit rearward can also be done without requiring a new cover.