I think 3-4 hours is long enough for pheasant. Maybe even less. A really simple brine recipe/ratio is something like this:

1 gallon cold water
3/4 cup kosher salt
1/2 cup light brown sugar

You can add whatever herbs/peppercorns/spices you want as long as they're salt/sugar free. And when I cooked some Alaska spruce hens one time, I draped the birds with strips of bacon to add some fat for the first half of the cook before and then removed them so the meat would brown evenly. It helped a lot.

The best improvement to any recipe I've achieved is when I pre-brined some cut up chicken breasts for a fried chicken finger recipe. The cooked chicken fingers were literally bursting with juice. Without brining, they were kinda dry. This recipe here, but with a 1/2 hour to an hour in the above brine before breading them: http://foodwishes.blogspot.com/2010/01/let-your-chicken-fingers-do-walking.html