I was close, so close… Well ok, I had the correct manufacturer.
Thanks to persistence of and with the help of & crew over at , the mystery has been solved.
It appears to be an early 30’s Cadillac 353. While I cannot be certain Mystery Motor came from a the shape of the frame suggests that it could have. After a little more digging around I also found a that also fits the bill nicely.
Thanks to everyone for helping to track this down and if you have any other weird/rare/bizarre motor photos .