I also mounted the engine as far back on the mount as I could. What servo mounting block are you talking about? Do you mean the rails in the wings that servos mount to?

I actually got a 720 mah NiMH battery, it uses AAA cells, so I could move it back further in the wing and that did help a bit. The battery is mounted all the way at the trailing edge of the wing right now. The rx is just front of the battery. I may have to move the battery out of the radio compartment in the wing and tie it to the side of the fuse I guess. I really don't like adding weight to a plane to get it to balance. In fact other than gliders I have never had to, even after 15 years of flying R/C planes.

My real concern is that I don't think a 40 size engine will have enough power for me. A larger engine will just require even more weight.