ok that is a last ditch rifle but not the very end of the war, but close to it. Your bolt handle style and fixed sight give it away, along with no bayo lug and cleaning rod hole either filled in or not drilled.
What is interesting is the grooves for the dust cover are present, I wonder if the receiver was a left over. I should also note the receiver has a nice blue finish.
What I can't see is the end cap( safety) does it have a weld or a sun ray pattern in the middle of the end cap ( safety). if its a weld I would have a gunsmith look it over before you shoot it. also is the barrel interior chrome plated
I'm not a expert nor have I written any books on this subject, I just have looked at hundreds of these 7.7mm and own a lot of them.
I have a spare original dust cover, but this rifle would not have had one at this stage of the war, the last real slings I saw were sold back in the mid 90's when china opened up the arsennals and they were the late war cloth ones
overall a nice collectors piece the wood is in nice shape also
good luck with it, hope this helps