Nice rifle, my first is also an "O". I think your metal might be in better shape than mine, which has gotten pretty silvery on the g/l, receiver cover and most edges. Burton's Bible shows one near in serial to yours, 5776xx as having tritium sights. Mine is a little later, 613xxx and has phosphor.
You may find stamps, a boxed 1 or boxed 2. I think maybe these are refurb marks but not certain. Mine has boxed 1.
If he's still doing it, and pretty sure he is, there's a dude that sells replacement tritium vials with a selection of colors, can't recall price but I think 35-40 $ a throw. I can post a link if anybody wants to know more.