Congratulations if you have one. Please tell us about it.
I've had two Evans 400/360s and still have one. Cabelas sold my other one a while back. They are great rifles in a great caliber. The 400/360 was designed to be a better hunting round than the 303 and it is. It's a 300 gr bullet at 1950fps vs 215 grs at 2000fps for the 303. For reasons mainly related to bullet construction John Taylor maligned the catridge while heaping praise on the 400/350 which was Rigby's offering. They are essentially the same round with similar ballistics.
Based on the # of 400/360s that come up it was a very popular round.
I got my RCBS dies from Huntingtons and would recommend you try there for the dies. I went in with a couple of guys and had Horneber make us a run of 400/360 brass that has worked great. Of course you can use cut down 9.3x74. The load that I settled on was 54 grs of IMR 4350 with the 286 Woodleigh soft.
Good Luck