a big man with average big man skills for league III. lets say IS,ID,Reb 13 and Sb maybe 8 and OD 11, JS 15 would be a PF anyway in my opinion.
the problem in most cases is that the SF doesn't have enough Rebounding. and rebounding is very important especially in outside offenses.
after all it depends on the flow, because you need him to get the ball. if your gameflow is good, and he has some good secondaries along with his JS he will do very good in motion. i don't know about R&G though.