UMD.
Are you still with us ?

On the subject of a heavy plane. If the plane is tail heavy with a recommended engine in place. By all means put in a engine size that will need no ballest or butchering of anything. You can get the engines weights on a place like Tower Hobbies. Build a plane Put a weight in the engine area that is the recommended engines. Tailheavy ? Add weight till it is balanced. Buy a engine that weighs that much. Works everytime.

I found that all the wood ARF's took engines 2 X as large as recommended to balance.
Now we have planes that are scale, correct COG and fly vertically out of your hand. I like planes like that.