You can either go with the standard weatherby case or the improved such as the 300 ack Imp.
If this is for 1k BR, then the 300 ack is one of the best cartridges to go with. Not many shooting the 240s now, almost all use the 210 JLK, Berger or 216 Clinch River. Some are using the 187 Bibs bullets in 12 and 13 twist barrels and running 3250-3450 fps.
If you want to shoot the 240s stay with the 10 twist do not go to the 9 twist.
300 Ack Imp and 210s you can go with 11 twist.
needs 1-11 twist and tops out for 1k with the 210s at around 3000 fps in 30" barrels. I have shot the WSM for last 3 yrs in both light and heavy gun.
Would recommend the Broughton 5C barrel, Python action in right bolt dual port ($950 with trigger guard and tapered scope rings). That action is big enough to handle a 30" barrel.
Keep in mind the weight as it is critical. I just built a python (43oz)light gun with Broughton 30" 7S profile in 12 twist for Bibs, tapered to .940 at muzzle, fluted (6 deep ones that took off 1 lb) and brake. Bruce Baer laminated stock (4.5 lbs with 4 clear coats). This set up will allow me to make PA weight rules 16.5 lbs with a 1" scope and have about 1/2 lb left over. Rig is balanced perfectly for 1k work.
300 ack has standard dies from redding. Strongly suggest you buy your own reamer from Pacific Tool and Dave Kiff for $135. Too many variations on 300 acks.
Jim Carstenson at JLC precision will make you a custom FL size die for right at $100. See his article on www.6mmbr.com.