A .300 Magnum really shines when chambered in a long barrel, but long barrels aren't ideal on general purpose rifles that might be used occasionally in heavy cover. The solution then is to load your .300 with heavier bullets that give up less velocity when fired through a shorter tube. Lets consider a couple rifles that shouldn't break the bank, even with some gentle customizing: the Winchester M-70, and the Remington M-700. If one was to start with either of these rifles, he would have a reliable accurate rifle, but the barrels are a touch long, the finish leaves something to be desired, the stocks could be better, and your "all arounder" would probably benefit from a set of quality iron sights.
Twenty-two inches is about as short a barrel as I'd want chambered for a .300 Winchester, and is about as short as a standard contour rifle barrel can be cut without adversely affecting the balance of the rifle. Such a rig would still produce respectable velocity with bullets of 180 grs and heavier. Cutting and crowning a rifle barrel is pretty basic stuff for a good gunsmith, and should not pose a problem. Hunting rifles are exposed to the elements and to small mishaps which may occur over time. The best protection your rifle can have is a high quality bake on finish, CeraKote being the best one at the moment, and the color selection runs from gun metal blue to all sorts of subdued tones if you prefer the camo look.
With respect to rifle stocks, lets dispense with the idea of a factory or aftermarket plastic stock right away. These stocks do nothing to provide a suitable balance to the rifle, they are not rigid enough to enhance accuracy, and they do nothing to mitigate the effects of felt recoil. A fiberglass stock could be made to your specific LOP, and finished with a high quality recoil pad, I like McMillan stocks and Pachmayr Decelerator recoil pads, but of course they're not the only answer to the question. If you have an affection for wood stocks, the stock should be both pillar and glass bedded, and cross bolts should be installed. This will ensure not only a correct fit and support between stock and steel, it will uniform the action screws torque, prevent the wood from being compressed, and prevent recoil damage. Needless to say, a factory wood stock can be tweaked for far less money than the cost of a high quality fiberglass stock. Regardless of your preference, steps should be taken to ensure the stock fits you correctly, including the height of the comb. If the comb is ideal for the height of a scope, you might have to mash you cheek down hard on the stock in order to get a sight picture with irons. Shooting a heavy kicker with your face mashed into the stock will rattle your fillings. Despite the "drop in" advertising of various stock manufacturers, a proper bedding job is the correct way to proceed, and a correct bedding job will enhance accuracy. I've got in the habit of placing the front sling swivel on the radius of the forend tip. This placement prevents the front swivel stud from cutting my hand in recoil, and it allows the muzzle to ride a few inches lower when the rifle is slung muzzle up. Because I use the sling as a shooting aid, for me a sling attachment on the barrel is not an option, but barrel mounted slings are popular with some folks. Swivel studs should be glued in place to prevent turning.
With respect to iron sights, my taste runs to a barrel band front sight and a ghost ring rear. The difficulty here is that in most cases the ghost ring cannot be mounted at the same time as a scope (although there are scope bases with pop-up ghost rings) where an open sight can be attached midway along the barrel and not interfere. New England Custom Gun (NECG) makes very nice rifle sights, superior to most factory irons sights. Barrel band and ramp style front sights, and both peep and open rear sights are listed on their web site. QD scope rings are a good idea so that you can quickly transition from scope to irons, or from one scope to another. A general purpose rifle is usually equipped with a mid power scope, my first pick would be a Leupold 2.5-8X32; I see little value in mounting gigantic optics on normal hunting rifles. Perhaps if you want to stretch this rifle's legs, a big power scope could be acquired for those occasions. I've become a proponent of Picatinny rails as these offer the greatest latitude for mounting the scope.
Once completed, this rifle will be suitable for all occasions, and only your prowess as a handloader can make it any more versatile.
), in old cuttings and occasional clear cuts in northwestern N.B. Hunting white tail mostly and moose on a lucky draw year, haha. 
