If I was lucky enough to have a Colt .45 made in 1919, I'd leave it as is.
Since that's an original 1911 I would leave it alone and buy a new A1. You can leave it as is, but if it was parkerized and had G.I grips on it, then it would look like a military museum specimen. But I wouldn't put a lot of parts into it when you can get a whole new gun for not a lot more.