Gas!? You cant get a CO2 motor THAT big! And theres no throttle! [X(]

Petrol too big for this, although a Mackay 30 would be an option but too heavy.

Irvine 150 seems like a nice budget choice, I have experience with these engines as those the only brand I have

Electric-No CoG change and cheap to run, sure you'd need to replace batts but who cares

Saito-Nice fourstroker, after the inital cost fuel is as cheap as the Irvine, and maybe less fuel as well.

But this is just CONSIDERING! I am a long way off but it seems like a nice plane, I can see how they will perform tomorrow as well which will be good.