When balancing at CG, the tank is ALWAYS empty.

Can't help you with your engine question. I have an SE that I built a couple fo years ago (and still haven't had it in the air) and haven't decided on an engine for it yet. I am leaning towards a GMS .47 or maybe a Magnum/ASP .52.

I'm sure other will be willing to jump in here and make engine suggestions.

Good luck,