Generally it's been my experience that LMB over time will eventually extirpate GSH from most ponds in 6-8 years after they are introduced and you will see substantial declines within 2-3 years. Getting them established in ponds with LMB is darn near impossible, especially those without extensive shallow areas(few smaller ponds have these) and aquatic vegetation, few pond owners what large amounts of it.
GSH will eat FA, however unless they were in extremely crowded conditions which is unlikely in the presence of LMB, I doubt they will do much to control FA. One of my favorite baits for CC in ponds with GSH are GSH. I've cut open a lot of GSH in the 4"-8" range to use as cut bait and rarely do I find FA in their stomachs. Now in forage ponds where there are piles of GSH, I will see them feeding on FA.
There are a few species of Cyprinid that FA makes up a reasonable % in their diet. The brassy minnow (Hybognathus hankinsoni)and the central stoneroller (Campostoma anomalum) are the two big ones that come to mind. Unfortunately, neither would be suitable for your pond.
