NZ440R/T, yes, if all the owners would register, that would be great.
To your question. Yes, in my opinion, it is legal to write information down, taken from the internet, from cars directly (one that sits in a field, junk-yard or similar), or other publicly available sources. Journalists do that every day. Photo upload to a website only, if you have the copyright (you took the photos yourself or have permission to publish from the copyright owner).
I would not like to have my VIN or Fender-Tag secretly written down at a car-show from someone and it shows up on a website. If I see a Challenger and the owner, I refer to the Challenger Registry or ask for permission to publish.
If anyone sees a Challenger sitting in a field, please write the information down, take a photo if you have a camera around and register with your current user-id (you can register as many Challengers as you want). Wrecked or Parted-Out cars in the registry protects us all. If the VIN of such a car is published, this VIN is useless for the bad guys. Everyone can check the VIN in the search box of the registry, if it's one of those cars, it shows up (as long someone registered it before). Same with Junk-Yard cars, but please ask the owner of the junk-yard before.
And the VIN and Fender-Tags on the internet-auction-sites, I can't believe people are selling those. Yes, we absolutely want those VINs and Fender-Tags in the registry.
Please register those, incl. photo (I will not publish the photo).
JJ