Is it LEGAL????
Not really responding to your situation at all but since this has become a repository for title and VIN information I thought I'd clarify a few things, especially related to Kansas and Bills of Sale.
I've owned and worked for used car lots, for a fair percentage of my life and used to buy totaled vehicles from insurance companies and rebuilt cars that most people would assume are unrepairable. All that before I stumbled into a dream job as a software developer. I'm not admitting to anything below board but basically if you are honest with the people that you sell to and the State Highway Patrol inspects your VIN and gives you a title application then you are legal and ethical.
When you rebuild a totaled car the title comes back to you as a previous salvage vehicle. Before carfax and networked interstate DMVs, some rebuilders would "wash" a title (usually by "selling" it to someone in a state without branded titles) and get it back with a clean title. They would sell the vehicle without telling the person it was a rebuilder. It made it harder on the honest people because rebuilder became a dirty word in the car world. Sometimes you would get a clean title from an insurance company through a snafu or from an unbranded state. In those cases we were always upfront with the buyer and provided before pictures and told them exactly how it was repaired, even if they truly didn't care or know what it meant.
So I think it all comes down to intent for the ethical part of the equation. Sometimes we would buy two nearly identical cars with the intent of making one. Usually you went with the most valuable car. This might involve putting the rear clip through the floor pan and A-pillars and welding it to the valuable VIN and mileage car. Maybe even the interior from the donor car. We made the best car possible is the point. But we told the buyer expressly what was going on. I think once you do that, it's out of your hands. Law enforcement and the court feel the same way.
We sold a car repaired pretty much as described above. Two years later we received a summons from a neighboring county prosecutor. Someone had bought the car from the person we sold it to. They somehow got a title back without any branding for previous non-highway/salvage. They sold the car as such. The new owner had some work done on the car and while it was up on the lift the mechanic noticed the non-factory welds and undercoating along with overspray. These were usually late model cars so of course this stuck out. They told the owner what they saw. There wasn't anything wrong with the repair work but generally rebuilt cars are worth about 20-25% less than the same car without having been repaired. They went to civil court against the person that sold them the car who said he didn't know either. Luckily we kept the signed disclaimer that described all the work that had been done. That was all they needed from us.
Now... onto Antique titles in Kansas.
I'm not sure when the last time you tried to title with a bill of sale on an antique car, but if you try to do it now, they do a title search of course, but they also will not process a bill of sale for a vehicle that has been registered in Kansas.
I know this because I bought a 1970 Honda CL350 motorcycle in 2012 and had that exact thing happen. I went to the courthouse and they let me process the bill of sale but the state came back and would not issue the title. I had already done a lot of work to the bike so this started a year long fight to get a title. There are options, bonded titles, selling it to a friend in another state and buying it back, or buying a title bike with a frame. All of these things are legal, and ethical if your intent is as mine is/was, to keep the bike and enjoy it. I went with option D, find the original owners. The most legal way lol!
I did a title search myself and they send you a copy of the last title they had. The guy I bought it from said the people that sold it to him were dead now. But when I got the title it had 3 names on it! Through research I found out where he lived but no phone number, thanks cell phones... I went to his house about 50 miles away 4 times. I left him notes the last 2 times explaining what I was trying to do. The last time I put $50 cash in the envelope and said I wanted to pay him for his trouble if he would just help me out. He called me back and said he would help and that he was sending the money back to me. He I mailed him a vehicle limited power of attorney and duplicate title form to sign. He signed them and sent it back to me. I got the duplicate title mailed back to me and with the POA I was finally able to get "my" title. It was a learning experience. I'll never buy a bill of sale vehicle in Kansas again without doing a title search first. Yours would be easier since you have access to the records from your friend at the salvage yard.
Finally, I still have the title to the 1970 Dart Swinger I sold in 1992. The build sheet showed it left the factory floor on my first birthday, but I let it go anyway because I was broke and away at college. If I could ever track that body down again I would buy it in a heartbeat and would rebuild it from whatever was left. No fear of breaking the law no ethical internal strife.
If you made it this far... I know I'm long winded. I just want to say your original question was fine and I knew what you were asking. The point is as long as you sold it for what it was and not what it could be it's both legal and ethical. You bought parts, you're selling parts.