Hi Ron, You know steel helmets are my bag! Very nice specimen. I like the regulation camo colors and the nicely executed pattern. It's great that you were able to find an original replacement chinstrap. These are hard to lay hands on! I can't tell what's going on with the liner draw string. It looks like somebody may have tied the pad strings together. If this is the case, you might undo this post-war modification. I agree with what others have said about just leaving the helmet alone, but keep it in a humidity controlled environment.
The chinstrap on the other helmet in your photo is unusual. It looks like a field depot replacement of some sort - maybe Austro-Hungarian. I'd be interested to see better photos of that if you can manage.
Mark D.