I have this this airplane with a O S FS 120S-E. I would like to put a 3 blade propeller on it but not sure what size. currently I have a 14x10, should I put the same with the 3 blade?

The rule of thumb going from 2 blades to 3 is down 1 in diameter up 1 in pitch. So a 14x10 would be a13x 11 or the next size that is made