Most free flights are very stable laterally, and marginally stable in pitch. To convert to R/C remove most of the dihedral to reduce lateral stability and balance the aircraft with the cg just a little more forward to increase pitch stability. If the converted model is to be three control without ailerons, maintain on the order of 4-6 degrees of dihedral. If ailerons are going to be used and depending on your experience level, the wing can be flat, or just enough dihedral so that the wings doesn’t appear to droop. Incidence alone won’t effect stability. For a given configuration, pitch stability is only affected by cg position, forward cg is more stable, rearward cg less stable. Dihedral only effects lateral stability. It doesn’t effect pitch. Free flight models also generally have a small fin/rudder area to avoid spiral instability. For R/C you might want to increase it a little bit.

The pictures are of two free flight models converted to R/C. Both are three control aircraft with no ailerons. The red one had too much dihedral at first that resulted in jerky turns. I cut the wing and reworked it to the configuration shown here, and it has become one of my favorites. I have flown it with several two strokes and a diesel and now am flying it with a little four stroke engine.