If you plan to stock HSB, I would switch feeds to a higher protein percentage. Catfish can do fine on 32% feed, HSB will need something in the 40+ range, the higher the better IMO.
HSB do best when they have a forage species that is spine free and open water preferring. The 3 major species that fit that are the two shad species, gizzard and threadfin shad. Neither of which would be suitable for your pond. The last is the GSH, which hopefully took hold in the pond. If you are seeing 3" fish around, it appears they have. I would consider searching for a hatchery in your area that sells GSH and stock an additional 5-10 pounds of the largest ones they are offering for sale.
With a feeding program though, the HSB shouldn't have too much impact on the rest of your fishery. I would do ladder stocking method with the HSB and stock about 10 per acre per year each fall. So this fall, you would stock 50. Next fall, 50 again and so forth. Purchase the largest HSB you can find in the fall. These will usually be 8"-10" fish and are the faster growing fish from the prior spring's hatch. This should give you more females which tend to grow faster as well as better growing fish. If you stock every fall, you can maintain a well distributing age and size classes of fish producing a quality fishery.
