Others on this forum probably have some experience to offer, but for reference, my 175 racer ususally runs about 200° F immediately after a hard run, measured using an infrared temperature gun. I've not used a temp gauge with a spark plug temp ring though.
The oil injection systems have proven to be very reliable if you check that cable is hooked up, properly adjusted and in good condition, have good tubing, etc. Many people run a premix after a rebuild to help with break-in and as a backup until they confirm the injection system is working properly, then forget about it. You should get approximately 300 miles per quart of injection oil.
