While I'll be the first guy to say that's insane, you have to remember there's a lot happening there. Yeah, so it's supposedly an HP block out of a Challenger R/T. That adds exactly zero value to the block unless the buyer owns that exact R/T. There is nothing "HP" about an HP block except the numbers stamped in front of the manifold--which we can't see, other than enough to know it's a '71 440.
Look at it from the parts standpoint, though. Have you guys priced Six Pack stuff lately? The 340 factory manifolds are going for $1,500-$3,500 without carburetors, although 440 iron pieces like that remain less expensive. That particular air cleaner is near $1,000 and the air filter's another $140 by the time it lands on your doorstep. A set of numbers carbs can be $3,000. It's preposterous, but that's where we are. Yes, you can buy reproduction HP exhaust manifolds, but they're not correct. The real deal is still a four-digit proposition for nice ones. The dated dual-point distributor is in place with the correct cap. Wiring, correct coil, accessories and drives, blah blah blah... it's a lot of hassle saved in chasing parts for a restoration. Throw a $3,000 stroker kit atop it, and it starts to add up.
That being said, therein lies the rub: It's a 500-inch stroker with a fairly gnarly camshaft. Not exactly Platinum-tent material. The black exhaust manifolds are a failure, if easily corrected, but those cubes and that cam will not be happy with them regardless of finish. A points distributor on such an engine is foolhardy at best. It's got hypereutectic pistons, so corners were cut but where else? I'd call it a confused effort at best. Resto-correct guys usually aren't worried about berserk horsepower, and stroker aficianados are rarely looking for date codes.
If I had to guess, someone was sitting on a bunch of good parts for quite some time and decided to put them on a stroker engine. They likely profited heavily from it, but yeah--to assemble that thing as it is, you might land as far from the selling number as you think.