Would you be interesting in selling the gear sets only?
Are you running a moto shifter with a J-arm?
It seems odd that your otk karts have slack, I have an old tony kart esprit shifter from the 90s and its lever feels quite solid..
http://www.ebay.com/itm/Kawasaki-KX-80-Shifter-Kart-Pipe-/281456357364?pt=Race_Car_Parts&hash=item41881b2ff4&vxp=mtr
perhaps this would work? its kx80 and im sure it bends right bc its kart specific pipe.
can you send pics to carder328@gmail.com if you dont mind? a pic of the underside of the frame if possible as well