Not even Harleys started out as Harleys.... they were just a production run of frames that were hanging up.
Someone pulled an order for a Harley bike to be "built" and then the employee(s) drilled holes for a Harley badge(non bottle cap), painted a Harley color, added Harley chain wheel, proper fork etc.
Any factory frame could as well have been a straight Davis.
Most of these bikes we will never know. Provenance helps, but isn't the end all either. Photos can be altered, (I have a photo of the original owner when he was 14 years old...) yea, maybe.... bill of sale... can be made.... heck, even important birth certificates can be forged (we won't get into that here).
Maybe a parent bought a Davis to give Bobby, and Bobby's friend shows up at the ball park with a Harley bike. Bobby tells his folks, "I want (screaming) a Harley like Tommy has!!!! Parents bring bike back to the LBS. Shop takes it and changes into a Harley to please the all important customer. Bingo...instant Harley!
Another example: Chiefs, Napoleons, Elgins..... all same dig dang frames...... with different add-ons.
Lindy's? same thing...... began as plain Shelby frame.