Thank you all for your insight,
I'm at the moment training him with my guards, although I'm at the moment training my guards in inside skills, (as those with very low ID were hurting me versus active teams with look inside strategy) I'm going to train him in the following weeks until at least "average" IS, and then see what my team needs in general...
I'm not trying to make money out of this player, but I want to make him a good long term player for my team. I was thinking PF to be able to retire mine in 2 seasons-3 seasons. But I might wait for the next draft to pick myself a very big player to fill that role, and train this guy as a good SF.