I just got mine and haven't had time to work up loads but my intentions are that IMR3031 should be the powder for me. I will be loading the 300 gr bullet with a max of 55.0 grs although the early Lyman books say 57.0 grs as max. I'm sure you have looked at the Hogdon site for data.
http://data.hodgdon.com/cartridge_load.asp
Might also want to check over at
http://www.handloads.com/loaddata/default.asp for data from users.
Hope this is useful.