I like both your choices of H4198 and IMR3031. They have a good burning rate and fill the case fairly well for shooting cast boolits in a 30-30. I also like RL-7 for the same application. It falls in between as far as burning rate. plus it meters well if you throw your charges from a Uni-flow or the like. You should be able to find a good load with the powders you have on hand.