The thing about these cars is the genuine ones were never made by a specific factory.
They were aftermarket bespoke conversions mostly done by approved dealers.
There are a handful of very rare "full factory" AMG's that are really hard to come buy.
You would buy a 560SEC then be presented with a menu which would include everything from a nice set of wheels, suspension and bodykit up to and including widebody conversion with 6.0 dohc v8 and bespoke recaro interior.
No two were ever the same, I'm not enitrely sure they were ever all documented or collated in one place.
When new a full house AMG SEC Widebody was one of, if not the most expensive car in the world, therefore not many of them left as there certinaly weren't many to start with.