If you're looking for a lightweight action, there's not many better choices than a Pierce Skele-Ti short action. These actions weigh just 15.8oz with an integral recoil lug, titanium action, and steel bolt. If you want a steel action, you can go with our short Shadow that's stainless and weighs 21.1oz. The Ti is lighter, but costs about $350 more.
For the barrel, I'd do a 20-22" and something around a 2B or #3 contour steel barrel and have it fluted if that's an option from the manufacturer. If you're wanting a carbon barrel, I would do a Proof Sendero Light at the same finish length. The stock would either be a Manners UC or a McMillan Hunter's Edge. If you want one of the lightest, then I'd have Jack Keister build you a stock.