Save yourself some time, energy and push the easy button. If you want a legit 1/2 MOA rifle, buy a Fierce Fury or Edge that will spit factory ammo into teeny tiny groups consistently. Your going to spend thousands on your Remington 700 build that "might" accomplish what you are needing it to do. Why take a chance on something when for the same amount of money or less you can get a superior product and not have to worry about getting your $$$'s worth??? No offense to your preferred gunsmith, I'm sure he/they do excellent work.
You stated that you have years to figure this out, that gives you the opportunity to do your research and choose exactly what you want in all areas of this equation. Don't sell yourself short, when a 6-point herd bull steps out at 600 yards and you can't get closer. Having a rifle in your hand that your confident in making that shot with is worth it's weight in gold. I'm not encouraging anyone to settle for a long range shot if they are not comfortable or have not put the time in at the range to take a shot of this magnitude. However, when you invest as much time and energy into a hunt as we hunters do. Going home empty handed because you don't have faith in your ability as a shooter or you don't have confidence in your rifle brings a lot of sleepless nights post hunt.
Whatever you choose to do, good luck and may the force be with you!