The Gasser has more room than most modern bikes. Risers are not the answer. Tall has nothing ever to do with it as your arm span is usually close to your height. Lately all new riders want risers. I have yet heard a short guy say he wants to raise the foot pegs! My son hops well. A few trials ago a group of Enduro riders bought a Beta to learn to ride with. First thing they did was put risers on the thing. My son tried to hop the bike, but the risers destroyed the feel of a normal riding position. What it did is take away the initial leverage point , making it something awkward to ride. Believe me Brian you just need time on the bike. You should try a vintage bike some time, if you get the chance.
My little boy at last weeks trial. By the way he`s 6`5 .