Your gun will dictate what you do more than anything I can offer. But my .50s with 1:48 twists both like velocities right around 1600 +/-. So with roundball, I get that with about 70 gr. And with 250-300 gr conicals, that takes about 90 gr. Both are very accurate out to 100 yards. But that's with .50s. Probably need another 10 grains or so to do the same with a .54, if I had to guess.
The only conical I've hunted with is the Thor 247 gr. On a close shot, it expanded beautifully but found against the off-side rib. Shot it far and it just zipped through. Nowadays, I hunt with bismuth round ball here in CA or hard cast in AZ. Both zip through without any expansion. But for an accurate shot with a ball of that size, it's not really necessary on deer or skunk pigs.
The only conical I've hunted with is the Thor 247 gr. On a close shot, it expanded beautifully but found against the off-side rib. Shot it far and it just zipped through. Nowadays, I hunt with bismuth round ball here in CA or hard cast in AZ. Both zip through without any expansion. But for an accurate shot with a ball of that size, it's not really necessary on deer or skunk pigs.