Well, part of the recoil system is the receiver extension, and you only mentioned the buffer weight and the spring. Never mentioned what extension you planned, and that's a GIANT part of the Recoil System on a Large Frame AR. Ditch that WC spring, right off the bat. Forget about it. WC doesn't always get their gas port diameters right, in their large frame barrels, and I have a pile of proof of that, because I run WC barrels on all my weird caliber Large Frames. Buffer choice, in company? Very good. I run alot of Slash's buffers myself.
What receiver extension are you planning? I'm asking you this directly, because of the buffer you listed, and I already know the length of that buffer. ,,,And, you have better options, that will work better, for this build.
I'm running them in my 12.5" and 13.5" .308ARs...