On Moki engines the control rod comes close to the exhaust port. I always use a metal rod, also you can use a ball link clevis on the throttle arm to space the rod away from the muffler. You can also angle it slightly to give you some more space. I would not use plastic in this case. In fact I would try to avoid plastic altogether for control rods. If you need the electrical isolation (gasser) use plastic clevises or ball link clevises.