I would consider using a custom action, by the time you purchase a Rem action and have it trued you are not far from the cost of a Lawton or GAP-7000 (same action I believe) or a Borden or others.
Bottom line, the 700 has some significant flaws that the Remington fanatics ignore and just put up with, but why? The custom actions can do away with the minimal extractor that fails so regularly, bolt handles that might fall off, small opening for inserting cartridges (even offering detachable magazines) and triggers that require rebuilding to be safe and function properly. Not to mention the design issue of the safety and trigger that is the big bugaboo that will not go away. I do suggest you look at having a Sako style extractor installed if you go with a 700, I just had another Remington extractor fail - the result is the case stays in the chamber after you shoot. The extractor is a throw-away piece of metal, surprisingly mickey-mouse but they work.
I have 700's and 40x's and shoot them a lot but they are simply not nearly as good as they should be. Matter of fact my push-feed M-70's are easier to insert cartridges into, have superior extractors and simple, reliable safties and triggers - they require trueing etc but they are nicer actions to shoot in my opinion.
Regardless, we put together rifles to enjoy them so good luck with your decisions. You won't regret using the .300 WSM