Yes, you will have to notch for a 331. Not for the rods to clear but for the rod bolts to clear. 2 of my friends are building 331s right now and I kept telling them that they will have to have the block notched, but I never saw it in person. I always heard on here that you have to notch it. Well one of them wanted to see for him self and thats when we saw it. So, thats getting done right now.