Those are average sized GSF.7 to 8 inches would be big. You really have to have a good idea of what is there before stocking suggestions decisions can be made. Putting in adult 4 inch + BG and RES would not hurt. Nor would stocking a few CC at 6-8 inches. The FH are a good idea but will likely be eaten. Over the next few mths see if any other predators are in there (LMB). I would feed the new fish and harvest a few GSF.