That is 156 Berger EOL is Poison at the speed. I have mine running at 3035 and it has crushed several deer and a couple moose. Highly capable round and despite the ammo shortage, Hornady has had a factory eldx and eldm periodically available for the 6.5 prc. Might be something to consider if you are leaning toward the 7mm. If 30cal, sounds like 300wm is your best bet.I built a similar rifle, ended up 6lbs 10oz bare. I am using a bigger scope because it was a light weight replacement for my 11lb 7mm LRM long range hunting rifle. I chose the 6.5 PRC for cartridge, this was 3 years ago, I'd still choose the same cartridge now. The Berger 156 EOL at 3040fps is plenty for my needs. I used the following components.
26in Proof Sendero Carbon 1:8 with capped muzzle brake prep and long throat for the 147s and 156s
McMillan Game Hunter Carbon Fiber Stock in Urban Camo with the Edge fill and 2 front sling studs - it was 23oz btw
Defiance Deviant Ultra Light XM Length Action
Defiance XM BDL kit
Timney 2 Stage Calvin Elite trigger
I am using the VX6 4-24x52 HD for my scope currently, 24ish oz. Makes those Coues bucks easier to see at 700 yards.
On scope bases I'd have Defiance pin their base on the action or step up to the -X and stop worrying about bases forever. Or, have them pin the Tallys on. I have used Tallys on mountain rifles and they work great. There are a ton of great 30mm picatinny rings out there. I'm using Seekins 34mm rings, a little heavier but solid.
If you can ordered your stock without pillars, but set up for them. This will allow your gunsmith to fit custom height pillars to perfectly match the metal to the stock. I think that 280AI will be a great cartridge. I'm more of a short mag person but the 7mm bore has a place in my heart.