You're about to go down a rabbit hole, but that's part of what makes collectible GI pistols so fascinating.
By "correct" I'm assuming you mean major parts like slide and frame. Bonus for original/correct bushing, spring guide, hammer, and trigger. The smaller parts are next to impossible to discern, but if the pistol was in service for any length of time, it's a pretty safe bet they've been replaced at some point.
Now, it gets sticky.
If the slide is original WW1 or WW2 GI, it hasn't been heat treated. The WW2 slies were hardened from the front to an inch or so back, and around the slidestop notch. Everything else is dead soft and not only prone to cracking in the port adjacent to the breechface, but also recoil peening at the rear faces of the lugs. This will show with a stair-stepped appearance and can also be present on the front faces of the barrel upper lugs. If this condition is noted, the headspace is excessive, and possibly dangerously so. This is why the US government ordered about a half dozen spare slides and barrels for every complete pistol delivered.
If the pistol has been rearsenaled, and the slide has been replaced with as mid-1946 and later "hard" slide, the barrel has also been replaced, and is suitable for use. Otherwise, it's not a good idea to shoot a original/correct GI pistol very much. Like, a magazine full to commemorate the Normandy landing or your veteran father's birthday or something of that nature.
Hope this helps.