your header says wanted but your 1st reply looks and sounds like "for sale" instead/ the engine in the pix looks newer than mid 70s.
if this is a "wanted" ad, why do you specify you want an engine made only one of those 2 years? They made that 11hp for many years.
something that trips me up is that within a given engine brand/series there are so many versions... crank length/diameter configurations, fixed throttle, several types of variable speed throttle, etc.