I don't know much about full scale planes but that one looks like a full scale with a Turbo prop engine.

That said with a 80" wing span and if no more that around 15-17 pounds most any good 40cc should fly it well, You could go smaller but the power would not be there if you need it.

Now if nose weight is a problem and you have to keep it down I am sure a 26-30cc would fly it scale like and not be any extra there if you needed it, you did not say what the all up weight is suppose to come out to be.

A 120 four stroke is equal to about a 20cc gas engine, But gas engines do not put out as much power per cc as glow.

Just think about a chainsaw, That is really all our RC gas engines are but just made for RC use, So regular gas with oil mixture and you are ready to go, Most gas engines will have some instructions on to how to mix the oil and gas for break in and after break in.

Milton