Hi,
It is kind of "cute" in my opinion. First I was thinking of MK Champion but then I remember they had only plastic (nylon) fuselage so that do not fit your epoxy fuselage. Then I was thinking of some Bridi model but I'm unable to see any "Dirty Birdy" or similar typefrom Bridi that fit your plane appearance. I checked also trentonrcflyers classic pattern images but did not see any plane that had a fuselage like your plane. Little difficult to identify. Seems like 1970th design. Maybe it could be found in some ad in Model Airplane News or similar magazine if one browse through 1970-1980.

/Bo