I've got an 85 mfi bird that's been kept stock and I was hoping someone could supply me with an average temperature range the header surface should get up to after idling from a cold start.

I had a problem with the engine missing and made it way lean while working on it. They would get to 450F in a minute and the plug wires/boots would start to smoke. I've since taken care of the missing and temps are down to about 280F. It looks good to me but I'm just concerned if this is too hot for idle what it may mean for highway.