Hard to say if they are original to each other. Just because it came from the CMPicon doesn't add to the argument. But if the finish looks like they match then there is a good chance they've been together since then. The SN indicates April 1943 and the barrel is 2-43 so they are likely original. I think that the PBS stamp then means that the combo was used to rebuild a new rifle with other parts in May 1944, rather than the barrel replaced on the receiver.

If you know your history about the Italianicon campaign the Allies were fighting hard to break the last line of defense before Rome and out of the Anzio area. Makes you wonder if your receiver/barrel was involved in the previous fighting, and then remade into a new rifle right then a there. You can never prove it but it would also be in the realm of strong possibility. Also makes you wonder about the previous user. If the rifle got that messed up to be sent back for major repair/rebuild chances are the user did too, or worse.