I agree with Stan that the Valmet O/U combination guns are very accurate as rifles. My .308, loaded with a .300 Savage handload of 3031 and a 170 gr. Silvertip ".30-30" bullet, will group 3 shots under an inch at 100 yards every time; many groups are smaller (this is my go-to handload in .30-40s also--doesn't kick but kills). I can do almost as well with a 168 gr. GC bullet cast of wheelweights (which are becoming a rare commodity in CA). It will not hold this accuracy for five shots, but this is strictly a hunting gun.
Problems: the Valmets, both the "Savage" and Valmet-branded 2400s and the later Valmet and Tikka 412s are not ideal bird guns. You only get one shot. They are very short and heavy for their length (especially the 412) and don't swing well, although they point well for most shooters. They tend to have a stock more like a rifle than a shotgun, and don't fit all wingshooters very well. And many rifle shooters, including almost all the old ones, need a scope. Many people find the scope impedes their wingshooting a great deal. Since they were originally designed to shoot birds "on the sit" (like we shoot turkeys), the shotgun barrel tends to be choked full, full, full. That can be fixed with a choke tube but be sure to remind your gunsmith that Valmet barrels are tougher than the proverbial woodpecker lips before he wrecks a reamer or two, and possibly your barrel.
I tried to solve the sighting problem by scoping my 2400 with a Weaver V-3, which has enough magnification for woods rifle shooting and can be turned down to 1X for shooting the shotgun. But while it works fine for the rifle barrel, I'm just put off by the scope on a shotgun barrel, and it makes the gun swing even more slowly. NOT a birdgun in my hands.
So I retired the 2400 from dual bird/deer duty. It would make a great turkey gun in areas where you can use both a rifle and shotgun. It makes a great single shot rifle and that's what I use it for. If you were hunting something that might bite back like black bears or wild pigs, it would be VERY nice to have the shotgun barrel stuffed with a slug or buckshot for backup.
Unless you can afford a drilling or a better-balanced combination gun (both pricey in my experience) I'd still go with a scoped handgun (if you are of Elmer Keith marksman quality, you can forgo the scope) to accompany your shotgun.
Slugs work in the woods, but out in the baldies where you hunt any deer within slug range is going to be running like the wind. The confession about shooting a whitetail with birdshot above aside (and that deer was flying, not running) I don't shoot at running deer; my last experience when I was a teenager led me to forgo those shots. They seldom end well.
I envy you your hunts in the Breaks, although I'm not mobile enough for that stuff any more. Good times....Good luck!
