The proper position is thus:

Sit as high as you can while giving yourself adequate clearance from the ceiling, so you can see more of the road ahead. Give yourself enough recline that you are comfortable and don't have to stoop.

Your palms should be able to touch the top of the steering wheel with a slight bend left in your elbows. If your arms are fully stretched when you touch the top of the wheel, then you're too far away. Leave enough clearance between the steering wheel and yourself, though, that you can twirl it around with no difficulty. If you're sitting too close to the wheel, maneuvering will be difficult.

You should be able to floor the brake pedal with a slight bend still left in your leg and your buttocks still in the same position. If you have to move your body to floor the brakes, you're too far away.

Those are the only things that really matter. The rest is up to you. ;)