Are you seeing a lot of the top of the rib on the Winchester? or are you looking flat down the rib and seeing mostly the bead? Before I started to take any wood off the stock I'd do the following, loosen the stock bolt and pull the stock away from the reciever. When you get it loosened (you don't have to take it all the way off), take some plastic playing cards and insert them into the gap at the top of the stock (in between the stock and reciever) trace a line around the back of the reciever onto the playing card. Cut the cards so that they match the back of the reciever, and then put them in and tighten the stock down, this will shim the stock and increase the drop (the same as taking wood off the comb but this one is easily reversible). This should get you in the ballpark, if you want to learn a little more about shotgun fitting the following two articles will get you started in the right direction
Gun Fitting and
Recoil pads. The changing of the stock pitch (shimming the recoil pad to change it's angle), is more important when shooting from a low gun (wingshooting, or FITASC), and in those situations putting a shim in that is thicker at the top than bottom will help keep your barrel down when you mount the gun. But for what you're describing (sighted fire with the bead as your sight) you need to lower the comb or put and adjustable rib on, unless you drop so low where you can't see the bead, then you'll need to get a few offset chokes (or you could have the barrel bent but I shy away from that).
Gordon