From what I have just written, you will understand that I consider the use of the word "incorrect" to be incorrect. You have a rifle that is probably as it was re-assembled and checked by an armorer long, long ago. This supposition would be strengthened if the head clearance checks out to be OK. If you now swap parts to make it "all Winchester" and present it as being original, you are, in fact falsifying it to achieve an end that was officially not necessary in service. And even if this is not your intent, you can bet that one day, when it is no longer in your hands, someone else will present it thus.
How often has this happened? No-one knows, but I consider it to be not unlikely that the percentage of "correct" rifles is now higher than it was at the end of WW2.
It's your rifle, and you can paint it blue if you choose to, but personally, I would check the head clearance etc. and if it shoots well, leave it alone. Just my 5c of course, but I am a shooter, not a collector.