Backwards head gaskets directs all the water flow into the front 1/4 of the block; the rear overheats. Water has to flow across the bottom, then up, and back across the top. I've seen it done wrong a number of times. Under heavy load, it'll boil the water in the rear and overheat everything badly if it's under load. One of the instances was in a jet boat. Because of the plentiful cold water and using the lake for the cooling system, it didn't show the problem except the gauge...and that went from normal to "pegged hot" faster than the owner noticed. Total loss. It was at WOT for a good 10 minutes like that before it melted stuff and started banging.
Additionally, if you want the 460 to burp well in a Cobra, make a hole in your intake manifold on both sides in the rear, drill and tap for small pipe to hose fittings, and run hose forward to your filler neck, which should be higher than your heads. You want the fittings to flow a tiny amount of water; make the flow path no bigger than 1/8" per side. It's just for air bypass. Do that and you'll never have trapped air in the rear even if the nose is pointed downhill when you fill the system. Without it...you may. It's hard to find a filler neck that works well in a Cobra. I forgot where I got the basis of mine; I modified it quite a bit. I don't like the big burp tank in the front; with a neck like this...there's no need for it.
http://www.racesystems.com/cobra/images/Running1.jpg