On my 750 with low drag bars, if I clip a 4 inch wide strip of aluminum on the speedo and tach it's enough to stop the wind buffeting my helmet.
Doesn't need to be all that tall. Similar to the way a bug deflector works on a car, just enough to get the air moving upwards.
The aluminum I use is a strip about 11 inches long, 4 inches wide with the ends curved slightly to wrap around the gauges, used a pair of large hose clamps to hook it on. Makes a noticeable difference when riding and is easy to remove, and stores under the seat, great when a short ride turns into a long run, and it starts getting cold.
The air hits me just about mid forehead, found out by accident, had to carry some crap home and over the instruments was the only place to put some of it, noticed the huge change in airflow, and experimented.
Seeing that the 4" strip deflects the air to my forhead, I'd say you'd have to adjust for your height
Also, it's painted black on mine.
Do like I did and experiment with thin plywood to get the best width
Ken