I have been flying mine for a couple weeks now, with an TT 36 heli motor, tail wires, and standards for receiver and servos. mine weighs in at 3lbs 13 oz, no lead anywhere. I moved my battery pack to under the radio tray, and used a miniservo for the throttle, next to the tank.

Why would you want to run a 12 oz tank? That is twice the size of the original tank. I installed a 4 oz right from the get go, and get 15 min flights routinely. Would prob go 20-23 mins if i were just puttin around doing touch n gos. A ys 63 is overkill for that plane. If you end up around 4 1/2 lbs on this plane and it is going to lose alot of its floating abilities. Also, there is not enough room to mount a 12 oz tank in the plane, and still have it balance without alot of ballast in the back.