N226WR was registered but there is nothing in the airworthiness file. I have access and looked. That means that it was likely registered but never completed to the point of getting an airworthiness certificate. The registration expired and was the reason for "de-registration"
One thing you can try is to use the letter to FAA that kitfox has on their website
https://kitfoxaircraft.com/wp-conten...ssue-Rev-B.pdf and try to use this along with the build documentation and pictures from previous builders to certify it as a new airplane. For a homebuilt the serial number isn't strictly necessary as when completing the paperwork you can specify any serial number you want. Just whatever you pick stays with it. Essentially the clean sheet approach.
You may also be able to get the registration for N226WR into your name, but this requires the paper trail showing ownership. If the gentleman on the expired registration for N226WR is willing to give you a bill of sale for the airplane then that should be all you need. Otherwise you need the bill of sale from him to the next guy to the next guy.....