I personal would not bother with the 86 kx motor, too many part now getting hard to get , 86 also looks like it has the mildest port timing compared to later motors
It is going to be no advantage to get later crank and ign?
A TZR motor will put out more hp than the kx without any vibrations or surging issues
alot of work for very little return
Here in the UK u could buy a complete tzr for less than the price of a kx motor
good luck if you are going to do it but u would be bettter getting a 89on motor