JPETERS , I also own a Goldberg Ultimate , have O.S. Supercharged 120 in it . I did away with the split elevator pushrod and instead now run two servos mounted just in front of the horizontal stab with one servo reversed for pushrod symetrey . I run carbon fibre pushrods on the elevators with ball links (440) on the servo end and dubro 440 locking gold clevis on the elevator end.Rudder is via a single hitec 605mg servo mounted towards the rear of the wing using Dubro 440 pull pull system. Fuel tank is mounted on C.G. I think a Saito 150 would be perfect for this aircraft as it's got a lot of drag being a biplane and it would give you unlimited vertical. Don't know what the Saito weighs but i utilised the dual elevator sevo idea on mine to help cancel nose heavy C.G. as the O.S. 120sp isn't exactly the lightest 4 stroke around. Anyway , hope this helps and good luck ,the Ultimate is great bipe!