I just bought a Dec. 1942 manufacture m1903 - last month of production. It has the starting cuts on the bridge for the a3 rear sight, as in this picture
Attachment 110882
I saw a nice article once on these - some tooling had been switched to a3 already, but supply of parts in the bin dictated whether the receiver was finished as an a3, or m1903. My google foo can't seem to find it again at the moment.
My rifle wears a brand new CMPicon c-stock.
There are plenty of WW2 m1903's out there that were "altered" by simply throwing them in a hunting stock. Many were taken very well care of too. If you want a shooter, this is probably the cheapest route to go. you may need a new front and rear sight and, of course, stock and handguard. Plenty of articles and posts on here about how to bring one of these back.