+1 on repairing what left of the original, not restoring, just work with what's there. The replica would also be nice. Don't erase the history that the original in original condition has. The bike would be fantastic to have though wouldn't it!
On ebay they have leather helmets all the time, see if one is close and paint it up to match
That bike (a CZ175 Scrambler, about a 63' or 64') was a loaner from the Jawa/CZ Factory Rep for the area. He did that now and then, to get the bike name
Out there for folks to see and become familiar with. Sure wish I'd been old enough at the time and could have done it too! the bike (of his) that I wish I had (that that helmet was used with most), was a Jawa 250cc (engine was from what was known as a early 50's Jawa Perak 250cc and the frame was modified to resemble the later model Swing arm models. he lengthened the swingarm and the forks so that he could use 19" wheels (which he laced up himself), he built that old engine to fly, using factory modification info, specs, drawings and such. he used an early BSA Bantam gas tank (took it off of my little Jawa 50, since I was riding my Jawa 125 by then). He painted the frame, swingarm and forks gloss black and the gastank, fenders and such a Metallic Purple that he mixed up from what he had on hand. I got to spend some time with that bike while I was in High School.
I got to graduate from my 125 to his 250. And I was in Hg Heaven! There were some Honda 250 Scramblers around back then and that Purple Jawa would blow the wheels off of them in a heartbeat.
And I took great pleasure in doing it too!
Sadly, I have no pictures of that one and I don't think Dad has any either.
I DO have an old early 60's Jawa 250cc bike that needs lots of work, that I'm gonna try to duplicate my Dad's Purple 250 Jawa.
Here is that one that I have.