"Gear bound"?? I've been in karting for 50 years and don't know what that means.
Assuming this is the controlled LO206, there's an RPM limit. I would want to reach that limit that about 3/4 to 7/8 down the main straight. Gear accordingly.
Driver size; at this point in your driving career I don't think it makes a whole lot of difference. Just get the overall gear ratio right.
Make sure the clutch is holding the engine at peak torque coming out of the corners. Very important.
Find out what trail breaking is, avoided if possible.
Learn about air density versus jetting. Very important.
It's learning to drive is just as important as learning a set up. If you achieve proficiency in less than a year. It took me 3 years. I loved karting so much I stuck with it, eventually learning how to drive and how to tune.
Tuning; air density and jetting go hand-in-hand. I have this idea tuning is's severely limited as far as tuning with the L0206. Work with it.
Not all L0206 engines are created equal. There's good, there's bad and in between.