I'd build a first rifle as a general purpose, do all rifle. Ammo sold at Wal Mart logistics. .280 AI is a rifle nerd's option, which I love, but wouldn't choose. Having 3 sons, I have been down this road, and they may not be into this like you are.
.30-06 on a long action is a forever useful option for any level of shooter.
Proof barrel at a handy 22 in and a brake/supressor mount. Thunderbeast Dominus CB maybe.
Honestly, I've never saved money building a 700 and vowed not to do it again. I'd look at a custom from the start.
If you are set on the 700, have a good smith work over the 700 and a Badger rail for the top.
Just a thought…West Texas Ordnance switch lug might give you a switch barrel option too, but require a little work on the chassis inlet.
Cerakote to complement the chassis of choice.
Good sling.
Arca mount options with the mdt chassis.
Add a modular bipod and a nice case with tools and cleaning gear.