Yes, I apologize for the sidetrack.
Where I looking to build a lightweight, switch barrel rifle in the basic format you've mentioned:
Defiance anTiX - guaranteed headspace, lighter by almost a 1/4 lb, integrated 20 MOA rail rather than separate pinned rail, integrated recoil lug rather than pinned, same footprint, I'd have it nitrite coated. It's more expensive but if you're going all in, I'd rather throw a couple hundred more $'s toward it for the integral base and recoil lug...and save the weight.
The Defiance action wrench is $125 and has been great for my use.
Lilja prefit barrel - light contour stainless in chambering, twist, threaded, etc that you desire. I've got prefits from Lilja and Proof (carbon). Light contour stainless will be noticeably lighter.
Grayboe Trekker w/Hawkins M5 BDL - give you the freedom of longer OAL than most AICS and is more comfortable to carry in hand, a chassis feel to the stock at a lighter weight, easier bolt manipulation than from a chassis grip (unless a thumb rest is on the chassis). Bed the lug with barrel completely free floated for barrel changes. The MDT is fine if you desire the foldable stock and I'm not arguing against it but I'm neither here/there on a folding stock.
Scope of your choice, the 2.5-10x42 is a great scope. I'd probably go with the S&B PMII 6x42 but that's just my prejudice.
Seekins 30mm Lows for rings, but there are lots of good options.