If it's still dumping fuel out of the overflow you either need to adjust the height or replace the float and needle.
Exactly how bad was the header glowing after you rode it? If it was just 6 inches or less away from the engine you can consider that acceptable, but if it's glowing bright red all around the bend it's definitely too lean. If you're on the throttle and it's glowing it's not going to help to change the fuel screw, that only affects the fuel mix at idle speed, gotta change the needle height and main jet above idle. If it's dying at idle it's probably still lean on the idle circuit too. If you start it up and just let it idle will it glow red or does it only glow once you start riding it? Does it backfire, cough into the carb, etc. when it dies, or does it just quit?
If you have something inside your exhaust rattling take it off, point the inlet down, and shake the hell out of it like a madman. After my exhaust sat in my shed unused for 3 years I found that a family of mice and possibly a small squirrel were living in it for some time. Among other things I dumped about 15 acorns out of it, some fiberglass insulation, and a few feathers. Started it up and even more blew out of the other end. It's likely that whatever is rattling inside it just fell into it while it wasn't installed on the quad, and can be removed by shaking it enough.