@Tim sent me some info this morning that will take this project to a whole new level. Hoping to share more here soon.
So little update, PHOTOS FOUND! Working with a guy on the 60's history but nothing concrete yet. @Tim came by to look it over and made two great observations. The stainless trim around the mural is 46 ford window trim and the square holes in the tailpan are sized right for 40's chevrolet or ford tail lights and the pontiac tail lights where likely added later. I've got the story from 1970-1978 1969/70 cars bought by a Vic Lynn somewhere near Elkhorn WI It was driven wearing a red/white (I'm thinking yellow) paint job up until about 1974 when it gets painted chevrolet brown metallic. Somewhere between 1974 and 1978 the mural was painted by a Jack Cominski of Spring Grove. Unfortunately Vic is no longer with us and his son has been more than helpful contacting some old friends who might know more.
Such an awesome hot rod puzzle. Finding tell tell signs of different versions , different lives while moving into the newest one!