Lucky you! The painted number over a number is known to be a Japanese Navy marking on Type I rifles and I think on Japanese VZ24 rifles too. It seems the Navy got the short end of Arisaka distribution and had to buy rifles from Italy and Czechoslovakia. The marking, I'm guessing, means something like ship #11, rifle #45 but that is not known for sure.
Both the Japanese and Chinese bought and used P series VZ24 rifles. The Japanese captured a lot in China from the Chinese (before delivery?) and used them, only to give them back at the end of the war. The Chinese often stamped the stocks. Japanese P series VZ24 rifles are sometimes identified only by the Japanese characters painted on the original sling.
The two small stock stamps are first and third, or inspector #1 and inspector #3. The large stamp is as yet unidentified. I suppose it could be a Japanese rifle that was stamped by the Chinese after the war but there seems to be no way to prove Japanese ownership or use. That is, unless your serial number is P49938 or P49940. My receiver and stock serial number is P49939.
Yours looks like a vet bringback. I heard a story that a lot of them were found in new condition in a warehouse in the Phillipines. Mine has no import marks but could have missed being stamped by the importer. Or, it could be a Korean War vet bringback.
Here's my Chinese P series: