Thanks folks. I guess what I'm really looking at is a tactical/sniper set-up and didn't even know it. You've given me some wonderful ideas. Thanks again.
Agree with OlYeller on this one, the Savage would be a great place to start.
Probably the best out of the box bargain out there currently.
As you spend more time and practice you'll see what your yearnings are.
Better to do that before spending a chunk of money on a custom build.
If you think you must spend to money for a custom tactical rifle, look at GA Precision (Kansas City). George and his folks are building some very nice rifles. Or you could check with Preston at Surgeon (Prague, OK) to see if they can suit your needs.
And, if you decide to go with a Rem700 action for a build of a .300WinMag, you'll need an LA - a long action (not a short action which was mentioned by someone earlier above).