a point is...
keep training them as PF/C
and search transferlist for a potential SF who will need som inside skills and have a good all around
yo train them till you're centers are strong eonough and then you chance to SF/pf
you will no lose training and no losing "value" in yor matchs.
Trining 1vs1 (forwards) willbenefeit you on driving handlingJump shot and ID so if you also give them 2 or 3 trins at jump shot for same position you will made a very interesting PF :D