Had OS 40 FP's on mine, flew great but had short flight times(8 min) due to the small tanks.
I used the "X" shaped flat motor mounts that mount to the engine back- plate and then to the firewall on rubber mounts, also mounted the engines on their sides so the mufflers pointed down under the wing.

Don't glue the nose cone on, you'll need to get at the nose gear for maintenance. I glued mine together for a tight fit on the nose of the plane and held it there with a 2 inch piece of Scotch tape on each side. Mine never came off.

These things land just like trainers.