If you are considering upgrading to a custom action I would recommend you check out the McMillan
G30. Of all the upgrade 700 style actions this one is my favorite for a number of reasons.
1. Highest grade of materials, 17-4 PH stainless for the receiver and 9310 bolt.
2. Rear bridge is dropped down to accept all Rem 700 scope mounts. Most custom actions take the easy way out and keep the rear bridge at full diameter.
3. Large loading port gives better access to the action and makes loading and unloading surer and easier. I am not a fan of the reduced size loading ports in most custom actions as the minimal gain in stiffness is not worth the hassle of loading when I have gloves on or am in a hurry.
4. Functional bolt fluting. In my opinion fluting is done to give dirt and crap a place to go when operating under less than sterile conditions. Every other action I have seen stops the flutes short of the bridges and therefore it serves no purpose but cosmetic and a very minor reduction in action weight. The flutes on the G30 run under the bridges. The flutes are also not cut with a ball nosed endmill but rather with a milling cutter that produces steeper side walls in the flutes and more efficient flute geometry for breaking ice under the bridges.
5. The G30 has an enclosed cocking piece and it will help prevent gas from reaching the shooter in the event of a catastrophic case failure. I had a major case blow up in my G30 264 Win Mag (The one you shot) from a major screw up (bore obstruction) and no gas made it to my face.
6. The best designed primary extraction cam I have seen.
7. The firing pin/cocking piece can quickly be removed from the bolt in the field without tools.
8. Being a push feed action allows the G30 to have the spring-loaded plunger ejector that ejects the case sooner in the cycle than a blade style ejector. The problem with a spring loaded plunger is, very rarely, it can stick under harsh conditions or more commonly if you are running high pressure loads and shaved brass accumulates in the plunger bore. As a back up the G30 also has a blade style ejector that will kick the case out at the end of the stroke if the plunger ever fails.
9. The claw extractor is an improved Sako style.
All this extra costs extra and the G30 is pretty pricey but when you consider the cost of the G30 vs other custom actions you are at least getting something other than a warmed over 700 with a shiny polish on it. (Said in jest and not meaning any disrespect for any one elses favorite action)
On the 20 MOA bases I saw a Weaver 20 MOA rail the other day in a gun store for 30 bucks for the Rem 700. It was aluminum so it will be pretty light weight for a 1 pc rail.
For me I like the Rem 700 for the economics and solid functionality but if I want a better action I need to actually get more than a tighter fitting bolt, smaller loading port and shiny finish. The G30 is darn sure better. At least in my opinion.