I've used the .50 & .54 cals for years and agree that those would both be very effective loads.
IMO, the .54cal conical is probably overkill for deer, as the 230grn .54cal ball is outstanding in it's own right, but if you've already got the rifle sighted in for the conical and might go after bear with it as well, probably makes sense to leave well enougth alone.
Good luck