The "weird" three horizontal lines with a number underneath are probably the remains of the
waffenamt stamp.
As for conservation of value, take the action out of the stock, give everything a good rub-down with balistol or similar, and run a couple of patches through the barrel. Nothing else needed, American collectors frown on refinishing etc. The mixed parts character isn't naturally a death sentence to collectibility, many guns got rebuilt in the last months of the war, and Germany did not renumber.
If you want to shoot it, give the bore a good cleaning, and take it to your local gun smith to check the headspace, for any obvious defects, and, more important, any bubba work, e. g. rechambering in 8mm-06 (very popular after the war due to a lack of 8x57 ammo).