Many of the bikes I own, or have owned, would have been built up as the purchaser wished. In other words, there wasn't always a "stock" build. In fact, riding in the 70's that was the only way I ever knew to build up components. If a derailleur got trashed, it was replaced with something else and no consideration to whether it was Campy or whatever. At one time I was enamored of French bikes. Going back in time, there were no "groups" to speak of - although one can certainly look at a PX-10 and see what would have been original spec. (And even that was often a moving target.)

I prefer to step into my time machine and get out at 1968 or '73 or whatever. If I were to get a new frame at that time, how would I spec the build? That approach appeals to me much more than "catalog restorations."

And this is the best part: we all tend to approach it a little differently here. Folks are (usually) nonjudgmental about such decisions, and that's primarily because there's usually no clear cut "right" or "wrong" way.