Hmm...
Delta 100, Tmax 100 etc all run innumerable rings round Panatomic-X by every measure apart from resistance to gross user error. Every competently processed sample of it that I have had through my hands has had considerably stronger visual granularity than you might think (as in current 3D-crystal ISO 100 levels) - and there are tests done on Kodak's own test equipment that show how close run the granularity difference between 80s Panatomic-X and 80s Plus-X was.
Verichrome Pan was not a double coated emulsion (it was 135 Plus-X's emulsions coated in 120 as a budget film) - 1930s-mid 1950s orthochromatic Verichrome was the double layer coating. The advent of controlled crystal growth technologies etc by the mid 50's eliminated the need for excessive layers, relative to layer thickness & speed. 'Long scale' is a nonsensical phrase invented by Kodak Super-XX fanboys (with column inches to fill) who hadn't clocked that pre-Tmax, Super-XX was Kodak's principle 'general purpose' B&W sheet film, with most of the rest of Kodak's sheet offering being aimed at more specific purposes that were largely baked-in to the characteristic curves.
Leaving that aside, Harman would probably happily make you a 3D crystal structure ISO 50 film of whatever colour sensitisation and curve shape you wanted - if you were prepared to underwrite the R&D and production costs...