Well it also depends on what level you are talking about. If you are talking about at the NBBA level then I think a nice JS/JR for a balanced AF that can play about every position is about 16/9 and then at least 14 IS. Obviously this will be lower for D.II and even lower for D.III. I think it would be easier to help you out a bit if I could see your SFs current skills.
Murray/Harris/MPJ/Grant/Jokic - 2020 NBA Champs