I've got the exact same pistol in .40 and also wondered about the date (I'm not original owner). My S/N is prior to yours (909974) but the barrel has BE, which would be after yours if that's the date. Doesn't make sense unless the barrels were stocked separately and they just pulled one from stock when they were doing the final assembly. K. Littschwager was also the one who test fired and signed my target.
And, yes, Bar-Sto is the way to go. As you can see, I've got one of their threaded 9mm barrels in mine.
We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution but to overthrow the men who pervert the Constitution.
Abraham Lincoln