I will throw in a couple suggestions
1. if you have to open the bolt face, don't bother. Sell that bolt for $100 or more and buy a Pacific Tool and Guage, Dave Kiff bolt already to go and you can buy it oversized to fit your action exactly and even fluted. Better fit, smoother, better extractor etc. That is no brainer money and quality wise.
2. 300 WSM would be my choice of calibers. you can load the WSM long due to your long action. 30 cal has the widest choice of bullets from the new 210 JLK LB BT that are .680 BC, available right here in the US from full time guy, to the 168 Barnes TTSX etc. Guys are shooting the WSM to one mile in tactical comps.
3. WSM barrel life is 2-4 times anything else mentioned and you will want to practice I assume. My first WSM barrel had 2300 rds thru it, IBS shooter of the year just won with 4000 rds in his WSM. I have seen and had problems building guns for one bullet and when it does not work or is no longer available you are SOL. We have had posts right here on that.
4. WSM no expensive custom dies ($300-500) for wildcat. However, you can buy a Redding body bump die ($25) send it to Jim Carstenson at JLC Precision and he will make a custom honed FL size die with neck bushings for $80. Two week turnaround. Go to www.6mmbr.com
and look him up under the Tools link. Buy a Forester micro seater ($65) and you are ready to go.
5. Whatever caliber you use, go to Dave Kiff and get your own reamer ordered. $150 and you have it to rechamber everytime and no differences in chamber dimensions.