I don't know anything about the original Elgins, though they were supposed to be pretty good. I did have a new one, i.e. a Ti case with a Seiko mvt in it- nice watch, good price and very reliable, but nothing in fact to do with a real one. First things first- DON'T wear it until it's been thoroughly serviced and checked out by a very reputable watchmaker- check watch sites for info on who's reliable and DON'T go to the mall. If you have a big fancy shop in your high St, make sure they have a qualified watchmaker on the premises and aren't going to farm it out, then meet him and make a decision. Unless the back has been changed or worn down through age there should be copious info on it, but it seems something has gone awry there.
Once it's been serviced and regulated, I'd wear it for a week if you can without damaging it (job permitting) to get an idea of its accuracy and smoothness of movement, then save it for special occasions. Congrats on finding a genuine piece of American horological History.
Most vintage watches have no info on the outer caseback. It's all on the inside of the caseback or on the mvmt itself. When I say vintage I mean older watches from the 1950s and before. They started with info on casebacks in the late 50s and 60s.