So yours would be the second series (Or version) of the Mustang after the VC was dropped from the range.Now without knowing your engine number it would be a little harder to date.However if it was to be the same as mine,mine was build in 1979 but wasn't sold until 1980 as the new Series 80's range.
Not to sure about your carby cap it could have been changed or it may well be the original as they did change to that style during the 1980's.
It is know as a full crank as they are using a full crank.
Crank is like the one pictured here.I guess there called a full crank as where the conrod connects there is a balance weight top and bottom and the top connects to the flyweel and the bottom connects to the cutting disc.
[Linked Image]
A powertoroque engine does not have that,are not know as full crank engines.Sorry don't have a picture of that.
Engine number is on the bottom part of the crankcase opposite of the cylinder,like this.
[Linked Image]
Post your engine number up if you like and I'll try and date it for you.
Here is some other pictures of what the engine looks like.
[Linked Image]
[Linked Image]




Here for a good time,not a long time.