Hebe –
I don't know if you follow the vintage Omega market at all closely, but there is a company called "Watchco" which amassed a huge stock of NOS parts years ago. They have been selling the parts not only individually, but as complete watches, notably the desirable and valuable Seamster 300 model.
Now, based on your very liberal definition, those watches should apparently be considered "original", as they are correctly constructed from genuine Omega parts. Yet no Omega collectors that I know of would use that term.
Within the context of IWC, I wouldn't consider even a watch with a correct replacement dial (or hands, etc.), to be original. Should it be considered correct? Yes. Genuine? Sure. Original? No.
Taking it a step further, when a part is used that would not have been used when the watch left the factory, say a white date wheel on a black dialed watch, or a non fish crown on a model that was originally fitted with such a crown, I completely fail to understand how it might reasonably be considered original. Yes, the replacements may be genuine IWC, and they may even be the only remaining, logical option. But if such a watch were to be considered original, then the word has arguably lost all of its – wait for it – original meaning.
Cheers,
Tony C.