since my scanner is at my dorm, i had to take pictures of them...

in this drawing i said lowering the part i circle will give you less displacement for shifting but i was wrong. i'll explain it as i write more about this lol
also i forgot to write this in the drawing. the part A turns (kinda spins) as you move your shifter left and right

i forgot to add brackets for the main pipe/rod. i'll update it when i can
this is not 100% complete. but as long as there is no slack it should work
there is certain amount of force to put the shifter in to gears so slack=fail.
also in my drawings, pipes/rods are drawn pretty thick but using strong metal (steel? steel alloy? whatever...) it can be lighter and thinner also.
and the part that is labeled as B in the second drawing, that will have to be adjusted according to your preference.
if you lower the part i circled in the drawing #2, you will need less force to shift but you have to push it farther than when the part B is horizontal
if you make the circled part higher than the other side of the part B, you won't need to push the shifter as far as you would when the part B is horizontal, but you have to push it harder.
any questions, just let me know