Pushing a lead conical over about 1450 fps is going to provide a nice treat for your barrel. LEADING - big time leading. The physics of what might happen downrange won't matter much when you are trying to get the lead out.

I shoot mostly conicals of 400 grains or more and rarely go past 90 grains of Pyrodex or 80 or T7. There is a lot more to be lost than gained by pushing them harder. Likely to suffer would be accuracy, your shoulder, condition of the rifle, and your pocketbook - all for next to nothing positive in return. 80 grains of powder behind a large pure lead conical will hit like Thor's hammer and expand nicely at muzzleloader ranges. I've a .451 home cast that has mushroomed to a bit over .7 here beside me. That bullet was removed from a buck taken at ~110 yards distance.