those 4-40 pushrods are adding weight way back in the tail where it's hard to counter it.
If possible I'd try a couple CF pushrods with 2-56 hardware.

I built mine with Sullivan blue ny-rods and an OS 40 4 stroke.. it came out right on the CG without adding any weight.

Some things you can try is moving the battery up under the fuel tank if there is room.
maybe find a heavy spinner or try a higley's heavy nut on the motor to get the weight as far forward as possible.