I think either block will be fine for your application. The KB is a stronger block for more serious (1000hp+) or boosted engines. The Indy block needs finish machine work. Hone,line hone,deck that adds to its cost. I think you will be close cost wise with either one. I personally don't like the World Products blocks. The main support is no where near as strong as a Indy or KB. That's important with 4.75 stroke.