Hello.
I think I originally recommended this site to you
Unfortunately the only info I have is what I gave to you.
The shaft fits 85-04 KX500 so it stands to reason that a newer kick lever will bolt on to the 86 shaft.
What I don't know is how the newer kick lever will interact with the 86 chassis.
Here is a pic of the 86 Kick lever:
Here is a pic of a newer kick lever:
It's just a guess but I bet they will interchange just fine.