ORIGINAL: egrave
The plane I got is call a perfection the fuselage is 48" long the wing sits 7" from the fire wall the wing root is 12".I have place the battery under the fuel tank and the receiver is just under the front of the wing I use a K&B twister engine. I have 5oz mounted on the motor mount and 8oz inside the fue tank well and I still need 8 more oz on the motor mount to balance it.
If you can move the battery pack and the lead from the tank compartment to the engine compartment you might be able to lose some of the weight.
Our club had a pylon race in May. Rules were pretty loose and it was for fun only. Everyone had to use a World Models Sky Raider Mach II with a .46 or smaller bushing engine. Every person's plane was tail heavy. Several people tie-wrapped the battery pack to the engine mount, or built a battery box, and avoided adding any lead to their planes.