For the bullets you've mentioned, I'd say 100gr of 777 would be your max load - accuracy probably will be better down around 90gr.

Personally, I'd advise going with as heavy a bullet as possible - as they'll be more stable and accurate. That would mean the 275 Aerotips might be your best best.......just don't push them too fast. I REALLY like the bullets made by PRBullet..............their QTs shoot fabulously in my .50cal Knight................you might want to give Cecil a call there & get his recommendation for bullet & powder charge...............that man is just amazing.