Manti Muzzy Tag. Need Load Advice

I will be hunting Bull Elk this Falls, and need a little help with my set up. I have hunted muley for years with this setup:

Knight MK-85 54cal. Shooting a 250gr .45cal hornaday XTP with a sabot. For powder I use 100gr of 777. It has been a pretty good load.

I have some 300gr XTP, and have thought of just using these, and pushing to 110gr of powder.

I should also note, I have put the shotgun primer kit on the MK-85 so it is no longer shooting no.11 caps

And suggests on recommended loads would be appreciated.

Can your 54 handle 150 gr. Of powder? I use a 250 Barnes tmz with 150 gr.of triple 7. It's a perfect load(flat shooting for bl. Powder) I used this load on a 2013 pahvant elk at 290 yards. It has a 26 in drop. A 100 gr. Powder would be about a 45 inch drop and not enough velocity.

Bronco63 thanks for replying. I have never shot that much powder, but I will check with knight to see if they think it would be alright before trying. What caliber of TMZ were you using?