Howdy bigdanusa,
If you put the landing gear in the wing beef up the ribs significantly. I like the gear mounted on the fuselage right in front of the wing saddle.
I think you will be pleased with the OS 70 4 stroke. I do not think you will have any trouble with this engine. I would buy or borrow a tach to set the needle, it is hard to set a 4 stroke by ear. Let us know how the build goes.

Charlie