National Ordinance Carbines are not very valuable and not much of a piece of history. When Carbines were not readily available to the general public NO manufactured less than good quality cast receivers and used mixed USGI and commercial parts to piece together Carbines for commercial sale. Some have parts unique to NO Carbines and cannot be replaced if they break. They have a history of constant malfunctions due to poor castings. Value is in the $300-$400 range or less. NO also made receivers for 1903A3 rifles. They too are not very valuable and their safety for use is questionable.
The rifle isn't unsafe to shoot and, if you happen to have found a good one, may function just fine. If it's not a good one you'll have function problems. BTW - moving the peep forward raises the peep and thus it will shoot high. Sliding the peep rearward lowers it and will lower your POI.
Still get the shakes when the Honkers turn into the wind and drop their feet or when a little forked horn buck walks up my trail. I take kids hunting every opportunity I get. "What?? Haven't heard an Elk bugle in the woods??" Man, you haven't lived yet!!