I found that the cheapo metric M20 plug is cast aluminum (used as oil drain plug for cars). So, I drilled a hole right through it with an 11/32 drill and tapped it with an 1/8-27 NPT tap. That fits the ether injector perfectly. That way, I did not have to drill/tap the intake elbow and did not have to wait to mail order reducer bushings.
frank8003, yes, if all you want to do is completely remove the flame heater, you need three plugs (M18, M20 and the NPT plug, i think 1/4, on the IP).
If you want to install an ether start kit, you need to install the ether nozzle in the intake and the ether kit's thermostat into the truck's thermostat housing.
eagle, thanks for the suggestion of teeing the ether nozzle and the boost gauge off the same T fitting. I thought about it but decided against it. Good to know that it worked for you, though.