That's taking 8 hour days, 365 days a year. Ouch... And they have a fabrication facility. Unless that thing was down to a couple of rusted frame rails when they found it, that doesn't quite add up either.
Assuming they are all professionals and have access to tools and equipment that would be off-limits for a DIY enthusiast, that is an awful lot of hours to spend on a restoration.
The original 'Cuda never came with an 1100hp twin turbo 522 cu in small block and a 6 speed manual and completely re-engineered IRS and IFS with HUGE brakes and 345mm wide tires on the rear. Custom interior with additional rigidity built-in... and other things.
6000-7000 hours, not really that many hours for a complete build like this.