You might be going about this all wrong. The seat location needs to be set first to give the kart the proper weight distribution, about 40/60. Check with your chassis manufacturer for recommended seat location.
Next, many chassis manufacturers offer different length as steering shafts. Perhaps a longer one would work for you. There are also wedges available that fit between the steering wheel and its hub. They’ll give you an additional 5,10 or 15 degrees downward tilt to the steering wheel.
LAD Specialties customer / tony kart / rotax / kt100