72-2 trigger ring

[flashrs1988]

HI all, Some time since i have been on hear, as my insulation has been running fine for 2 years, how ever i now need to move the trigger ring from the crank shaft to to the cam shaft, hence the need for a 72-2 trigger ring ? as it will be driven a half engine speed....
my question is, what is the smallest tooth pitch you can use to get successful operation.

as the diameter of the ring i intend to use is 140MM and has a pitch of 5mm will this work ?

has any one tried this

any info would be helpful

thanks

Steve