Very pretty rifle, but definitely not "all original". It doesn't have sling attachment points (as you stated), and that lovely stock with "sissy pad" was not manufactured in 1917.
I would put that style of recoil pad no earlier than the 60's, probably newer. The action looks to be in great shape, though. With a sling, you'd probably have a decent 1,000 yard gun.
VERY nice birthday present! Wish I had friends/relatives like you have!