A Rem700 SPS in 300winmag is a great platform to start with. Load it with 208grain Amax or 210grain VLDs and you have an awesome longrange rig.
Annual Hunting Retreat and Amax Review
As for upgrades on your rifle, here are my recommendations:
Stock - replace the factory stock as it is a piece of tupperware. McMillan is a great stock. Also look at Manners. Personally, I have two McMillan A3s and a buddy of mine has two Manners T2s. His T2s have the suspension system in them and that is a nice rig. (suspension system is nice if you plan to use detachable mags). If you get a stock that does not have a suspension system in it, be sure to skim coat bed it and also consider pillars.
Barrel - have it recrowned. It is common for factory barrels to have a less than perfect crown on them.
Trigger - tune the trigger you have or go with a Jewel. Jewels are on my two longrange rigs and I just love them.
My 260 by MCR
My 300RUM by MCR
Your thought on having an 'accuracy package' done is a good one. My nephew's rifle had that done....
Nephew's Transformed Rifle!
Kevin Cram at Montour County Rifles (Montour County Rifles
) did all the work on these three rifles. I would highly recommend him to you.
Good enough response? any other questions? glad to help with whatever I can.