On most vintage American guns--Ithacas and Model 21's being fairly rare exceptions--the chokes weren't marked anyhow. So unless it's a collector gun--higher grade and/or field grade in close to perfect condition and unaltered--who cares if you open the chokes? And who will ever know, unless factory records (if available) are checked?
Not totally true. Without even commenting on whether to or not to open chokes A person who knows their guns can generally tell. Few "Choke Doctors" bother to use an exact configuration of an original. If you find barrels for instance with open chokes having abnormally long parallels they have almost certainly been opened. If both chokes are open but one barrel, usually the left one, has a onger parallel than the other then that barrel started with mote choke than did the one with the shorter parallel. If it is a brand, such as Lefever, which was originally bored with "Taper" chokes & the choke ends with a parallel section, It Has Been Opened. Serious Collectors look at these things, Hunters not so much.
Also on chambers unless the cone has been cut to a long taper it can be extremely difficult to determine whether it is original length or not. Many companies would cut chamber lengths to order. My 16 gauge H grade Lefever for instance, built in the 1907-1915 era has 3" chambers with standard length cones. Definitely not considered your standard 16 ga chamber, But, were they ordered this way or have they been lengthened?????
Both barrels on this gun carry full chokes so not much question on them.
