If he did exagerate, the plans I linked might not exactly match what you have..Unless he got a very early DynaFlite version before they changed it. Since I read it was the 40yr old version the plans/plane I linked were from that era. The DynaFlite version was different though from the MarksModels and older Jemco... MarksModels sold to DynaFlite probably 25yrs ago give or take, and DynaFlite took these types of designs and updated them, so the family of Mustangs they had did go through some changes... If this were the FunScale 60, I actually have those plans in my computer, but the .40 was smaller and different... and obviously there were a few versions produced throughout the years. I've had 3 of these, and now have the .60 size version, and I'm always on the lookout for these kits of any era. They're just that fun. Very memorable models. .
They all had the instructions written on the plan sheet though.. a formal/seperate manual wasn't written. Actually if you Google the plane, and search images, and hit on as many links as you can find, you might come up with what you need as well. These were all popular and fun planes.