1983 ford 460 Exhaust pipe glowing red on Number 1 and 2 cylinders only?

Off the top of my head I'd say you have a intake manifold leak, specifically at #1 and 2 cylinder which would be the front of the manifold, For a quick check spray some starting fluid or brake clean up into that area and if the RPM goes up you found the problem, if not, Humm... why just 1 and 2, generally a lean carburetor problem lights up both banks, and intake valves would cause a miss, interesting,

A red hot exhaust manifold would indicate a "lean" condition in those cylinders, as in they're not getting enough fuel for proper combustion and cooling. A 410 CFM carburetor seems a bit small for a 460 cubic inch engine. Maybe you need to go for a bigger carb OR check your intake manifold to be certain that those two cylinders are getting their fair share of the fuel.

The super-high heat coming on so fast suggests a VERY lean mixture, so you might first look at a compression test to see about the valves, as it appears they may be sticking or not opening far enough/long enough.

Vacuum leak, Exhaust leak, excessive lifter pre-load on those cylinders, leaking valve seats.

Do a leak down test...Buy a dual gauge leak down tester.

one inch thick 4-hole carb spacer is a nice enhancement for it, as well.

Consider buying a $10 box of rocker arm pedestal shims to shim out all but about .010-015 in lifter pre-load.

camshaftshaun@gmail.com

Vacuum leak.

Fresh air into cylinder = excess 02 = higher burn temps, assuming rebuild was a good one (valves ground and working as they should).

An exhaust will normally do that when it's running lean. Recheck your carburetor.