The hardest part of all is finding a truly correct and un-restored HP Comet to verify the claims and conditions.
Honestly doubt the "25 unit" claim. Stroppe or DST (I'd need to reach out on that one) did build a limited run of 289 lightweight drag cars for the lower FX classes. Essentially their 427 build, minus the FE mandated shock tower relocation and steering revisions.
I do know that a legit HP will have the solid lifters, dual-point dizzy, and the large balancer ... in addition to the "D" warranty code and the Cyclone trim. It will also have the 9" rear axle with the tapered tubes and the "Daytona" pinion carrier and IIRC the big prop shaft. Any car that still has the build sheet intact will have either a teletyped "Dragster" or "Special Dragster" in the notes section or an inspector's crayon notation.
That said, a clean Cyclone COULD be built to those specifications rather easily, assuming you were starting with a K - manual transmission body. Adding Shelby GT350 proven bits would get you a very nice, roadable car that's just about the right size for touring and driving the two-lanes.