The 1st rifle, 460890, falls just outside the group of rifles built by Winchester for (I believe) the Marines for Vera Cruz. If it is part of that group of rifles, its serial number got left off the list.
The 2nd rifle, 348673, falls kinda in the middle of nowhere, and is the second oldest A5 mounted 03 I have heard of, but are you sure those are Unertl mounts (should be Winchester #2 mounts)? If so, it as not a Marine sniper rifle.
Are they sniper rifles? Don't know - haven't seen them yet. Could they be sniper rifles? Yep, or could have been used a door stops. We don't know. The 5th and 6th Regiments did carry over 200 scoped rifles to France. Many never came back. Is there a record of those rifles? I hope so, but we haven't found it yet.
Jim