Never heard of anyone doing it and thinking about it I believe it would be a TALL order (sorry). It depends on the configuration of the controls and if they lend themselves to being repositioned or extended. The bars themselves could be the easiest part. I would be concerned with the controls.
i have the same feeling. (6'4"). every one i have ever used the handles were too low. never got around to extending them. my mower had the same issue. those i just found a scrap mower and took the u shape handle and put it between the factory ones and had in essence three handles. just had to make longer cable for the controls. but that was only 2 cables.
the snowblower i use now is high enough.
i did have one thought, i dont know what your model looks like but if it is 2 tubular handles that point rearward. how about two u shape sections of tubing. butt the ends together so the u's curve up and then point forward. leave most of the controls where they are except the one or two clutch levers. if they are cable operated cut the cable and extend it (or replace entirely), if they are rod controls thats easy enough, do it like old machines and cut the rod use a stell tube as a coupler with some holes drilled and cotter pins, make it the length needed to reach the new bars. i have even seen universal joint if it needs to bend. bending over to move a control here and there is ok but i know constantly bending to hold onto a machine is torture