Individual header tube temp. Egt. Varies

It's hard to get the idle temps equal. Especially when the headers make a sharp turn right out of the port.

I'd double check my idle setting and not look at the AF ratio while doing it. Get the engine to idle it's best and then look at the AF ratio.

I wouldn't get excited about idle exhaust temps. If you really want to lose your mind, check an engine running alcohol. Most guys run them dead rich with slow timing. The exhaust temps go through the roof. So they add more fuel and take out timing and it gets worse. Some never learn.

Also, double check your timing at idle. You may need more initial. If the cam is what you say it is. 18-20 initial may not be enough.