I'm trying to get a feel for lenses available in the 360mm range and am finding that the Apo-Ronar and Apo-Artar's are ticking a lot of boxes. Complicating matters for me, though, is understanding the whole shim business--I get that shims are used for optimizing performance at distance, but assuming I'm looking at an Apo-Ronar in a modern, black Copal 3:

1.) Is there any way to tell I'm looking at a factory-installed shutter, or whether someone has done the job with "aftermarket" parts?

2.) How many shims should a 360mm have? I've seen sellers' descriptions of Apo-Ronars in Copal 3's as having one, two, or in the case of shorter lenses, no shims at all. Should a single shim ring be a danger sign?

3.) As of yet, all of the conversations I've seen about shims have been about Rodenstock lenses--do Apo-Artar's use them as well? Also, I've noticed the in-shutter Schneider's seem to sell for a bit more than do the Apo-Ronar's, which was surprising to me given the latter can have more modern lens coatings. Are there simply fewer Apo-Artar's out there, or is there a "pixie dust" reputation to consider?

Any insights appreciated!