I have an old OS 46SX on mine and it's a rocket!

One thing to look for is: The elevator pushrod comes up through the rear of the engine nacell - make sure that it can't flex at that point, or when you try to pull out of a dive, the airflow can push the elevator back down which greatly reduces the elevator's effectivness.

If it doesn't have any support back there, you can just glue a few balsa braces back there with a hole for the pushrod - so it can still move back and forth, but can't flex