Well training big men is expensive sport, and i am not sure that a team like yours you will be able to train them for long time. From the other side your PG looks like a very weak one.
So i think that is better to go with guards training (take longer to develop because you have to train more skills), sell the big man and buy an other guard to work among your your SF, or if you need a big man replace him with an older one. Thats my 2 cents