My Dear Monsiuer Smith-
please be assured we are not deliberately messing with you.
With the variations that do come out of Italy, ( esp from year to year) and the different angles of photography across the vendor sites,
you may actually find minor variations in the actual measured length of both barrels and housings across samples of the same revolver from the same maker.
In order to get exactly what you want, Your best bet might be to physically visit a bunch of vendors and pick through what they have.
My experience is primarily in the C&B revolvers but In The Past Italian revolvers were extensively hand-fitted and differences were extensive, even in the cartridge guns. Recent improvements in their machinery ( for which I am actually quite grateful) have led to more consistency, uniformity and better quality. Cartridge guns are pretty darn good out of the box, ( for their price) and at least the parts in Cap Guns ( ie Parts Kits) are now actually interchangeable. :-)
I hate to say this but you may not be certain of what you will get unless you have several samples physically in hand at a gunstore
or two and can actually measure things with a good steel machinists' rule and viewed through a powerful lens, and record the results.
Or just sort thru them until you find what you want.
Unfortunately "it is what is is" ; what comes in is what we get; and we are actually lucky to be able to get the wide assortment of features that we do at a reasonable price and pretty darn good quality.
When I can get to my "piles-o-parts" I could measure what ejector housings I have and post the results for you, but the problem then is actually identifying "what the heck I have" since I acquire parts lots cheaply and nearly nothing is marked :-(
Now, if you buy a new revolver and cannot abide by the housing length, If you can convince a person in a parts house such as VTI to physically measure ejector housings for you , you might be able to find one long enough, or get one that is longer and have it trimmed down.
If you have the revolver of your desire in hand and the ejector housing is not to your liking, it is entirely possible you may find a sympathetic smith who is willing to spend the time ( ie time == money ) to "find" a housing which is to your satisfaction, or even "grow one" a little longer for you.
yhs
prof marvel