"I am wanting to Rebarrel, new stock and muzzle break."
1200 is a long way indeed. For a dedicated long distance rig the Choate stocks are solid will easily accept a heavy barrel and come in a lot of left handed versions. Plenty of aftermarket barrel suppliers as well just check the vendors page.
Some rifles and calibers just seem to be finicky about the load and sometimes it seems to be near impossible to find one they like but I have found accuracy loads from the Nosler and Sierra manuals are a great place to start. I have several rifles that I didn't think would ever shoot only to eventually stumble onto the magic load.
Also converting a right handed stock to left handed is a pretty simple task if you don't mind tinkering. Just prep and fill the bolt cutout with epoxy and make a new cutout on the other side. A little paint and voila.
I have actually found factory stocks to be quite serviceable and easy to improve with materials available at most any hardware store. A little bedding, paint, epoxy, and manipulation of the existing material along with a little guidance from some of the posts and articles here can work wonders.
Here's a factory right handed detachable mag stock that has been converted to left handed, It has been epoxy bedded for a perfect fit to the action, the length of pull has been adjusted down to 12", a home made cheek riser added and a little paint. I originally bought the stock here in the classifieds as an old takeoff very economically and everything to transform it into what I wanted came from the hardware store.
https://i176.photobucket.com/albums/...ps58a82883.jpg
Good Luck and Tinker on