I don't know if there is really anything else to tell.
In the beginning it looked like this:
Hard to tell from the photo, has the bolt been bent? When it was new it was straight.
Winchester used the "Super-Speed" headstamp from before WW2 to the late 1960s.
The 1917/18, I have heard that means the action was made in 1917, but the rifle was not completed until 1918, but that may not be correct. Your best bet is to probably take detailed photos, register an account on Gunboards forums and post them in the Gew98 research thread here:
http://forums.gunboards.com/showthre...Gew98-Research
How does it shoot?