Thanks for the great pictures, I am surprised there are so many Steyr components (e/623) on the rifle, though we do not have many rifles recorded that have many original parts. Most of what we know about the variation is based upon JimP rifle, many of the others are rc's or heavily mismatched rifles, basically only barreled receivers with a part or two matching.
Your stock is a Menzel stock ("c" stock), typical of armorer spares and the G.29/40 program, the only other important thing that you could post is the barrel code, it would roughly date the rifle by the range of the barrel. While not perfect, usually I can date the barrel to a typical range of normal SDP production, though in this case, it being a depot build, it is less accurate but it might give us an idea of when the barrel was made at least. (the latest known barrel is a 1941 dated barrel, typical of the bnz/42 "f" block, a pretty high lot number, most are 1940 dated barrels)
The biggest question about these is when they were assembled, one can assume late 1941-1942 as the most likely range by known barrel codes and what we know of the "rifle shortage" expediencies that were part of the larger rationalization effort that occurred in German industry between May and December 1941.
Hi Loewe
I will take the riffel apart and post Picture of any barrelcode I can find.
JSNE