Thank you all for quick answers...

Ali, maybe you don't need to tell me twice to made bigger model...
Maybe 1/4 scale...

OK, but back to this G2.
I don't want to be "smart", I'm just talking about experience I have with my Ziroli F9F Panther. Here is a picture of Ziroli Panther and my Galeb (1/5 scale)...



...and as we can see Galeb is longer behind. Also exhaust tube is much longer than on F9F.
If I put turbine on place like option 1, from my first post, engine is almost on same place like in Panther. In my F9F model I need to add 500 gr ballast in the nose to made CG on right spot.

Second, fuel tanks on Panther is slightly in front of CG, because plastic inlets...



CG is in the middle of the tube in the wing, and rear part of fuel tanks are in that line. Should not be forgotten, engine is P 80, and I fly with 2 liter of fuel.
I haven't some big difference in flying capabilities with full and almost empty tank...

Galeb is much longer in the rear of the fuselage, and exhaust tube is almost 40 cm longer. Noses and wings of both airplanes are in the lines.
That is main reason why I want to put engine as far forward as I can...

After this explain more opinions please...

Regards

Mirce