Are kill switches mandatory. My TC 185 doesn't have one.

I'm about to do some WOT plug chops on my 74 TC185, but realize there is no kill switch. I'll still try it using the ignition switch, but was wandering if in 1974 they were not mandatory. 
Looking at photos on Bring a Trailer, I see the 75 models had the switch.

 

Using the key switch to do a plug chop may not be a good plan.  The normal method is to pull in the clutch lever as you hit the kill switch with your thumb or forefinger, holding the throttle in its same position. You could probably pull in the clutch lever as you let go of the throttle and use your right hand to turn the key?  Be careful.

Partzilla shows three different switch assemblies for the 1974 Ranger. It looks like the L model did not have a kill switch, but the A, B and M did.

www.partzilla.com/catalog/suzuki/motorcy.../right-handle-switch

I just did a Google search. It looks like kill switches on motorcycles were not required in the US untill the late 70's, and had to be within reach of the right thumb while the hand was on the throttle.