ive read ceramic coating headers cools EGTs by a couple hundred degrees at times so coating would help you. wrapping headers creates a heat sink and raises EGTs causing your engine to run hotter and with less performance. I would recommend using header wrap on your AC lines, or go to summit and get those fake stainless steel hose dress-up kits. I have full length hooker headers on my SBC in my monte and after 30 seconds you dont wanna touch the headers.

to check your mixture, use a vacuum gauge off of the carb or pull the hose off of the vacuum booster and set your idle mixture screws (base line is 1 1/4 turns out from all the way in) for maximum intake manifold vacuum. my SBC idles ~15 lbs of vacuum. Radical cams lower the amount of manifold vacuum. For an automatic transmition have someone hold the brake while the car is in drive, tune the carb. DO NOT REV THE ENGINE WHILE TUNING! I know that sounds dumb to say but if you ever have tuned your carb and "planed" it out between trials, that will get ya run da f**k over! lol

Hope this helps!