Could you cut the font off an 86 T3 seat pan, then plastic weld the kx500 seat nose to the front of the T3 pan, then get it covered in new hi-density foam, new gripper seat cover and wah-la, KX seat/tank junction and tecate seat and plastic.

P.S. I feel sick to the stomach that I just told someone to cut up a pefectly good Tecate seat pan..................... forget I spoke.........