Rong, another of our members, Rodeobob, has several HD8s a lot like yours but with Honda engines. The pictures I posted early in this thread are of his machines - if you search our archives you will find his posts about them. It does not seem unlikely that someone would have replaced a damaged Honda or Fuji engine with a slightly older Briggs engine if they happened to have access to one - I think only collectors try to match dates closely, most people probably look for an engine of the right size and power at the right price. However because your machine looks to be in exceptional condition for its age and model, it appears to be a potential collector's item, and it seems worthwhile for you to find out what engine it should have. That does not mean you should remove the engine it currently has, but you might choose to watch for an opportunity to acquire the "right" engine and store it, while continuing to use the Briggs.
To find the original colour, the usual technique is to look carefully at the machine and try to find a spot somebody had missed when repainting, or a place where the paint is damaged and you can scrape away the edge of the chipped place to look for another colour underneath. You might also post close-ups of any area where the paint looks to be sub-standard: there are several members who are skilled in distinguishing between original paint and repaint. Do not be surprised if the current paint is original though - it looks like a plausible colour to me. Try comparing it with the colours in some of Rodeobob's pictures.
