its always about condition and tooling. It seems good in the tooling department, condition who knows? For otherwise the same lathe, there can be magnitudes of change in value based on condition. A reconditioned round dial (done properly) vs a worn square dial, there is no question as to which is worth more and will perform better.
The fact that round dials are older than square usually means there usually is a correlation between age and miles. Usually, but its not a law. That's the main reasons round dials usually sell for less. 3000 vs 4000 rpm? pht. Who turns at 4000 on a manual lathe? And there is no difference in the bearings if you want to over clock the round dial. The idea that a made China lathe is going to be more accurate than a round 10ee in good nick is absurd....but of course without hoping on a plane none of us can intelligently comment on the condition.
For sure he's pushing the envelope, probably a bit outside of it. but we're talking about one the nicest, highest quality lathes ever made. If it is in fantastic condition, i.e negligible wear (we don't know, but I grant unlikely for that age) it could sell in that range.