Those Winchesters are pretty cool guns. Really nice action. I wouldn't do much to it. You might be able to find a shorter barrel from the links above, but that's probably all I'd do.
Go shoot the damn thing and get comfortable with it.
I like my Mossbergs for home defense use. I keep a 20" 590A1 with a red dot in the bedroom and an 18.5" 500 in the living room - hidden from view, but easily accessible. On the 18.5" 500 I have one of the Shockwave Technologies birds head style pistol grips. I very much dislike the regular vertical grips. They really beat up your wrist. With the more back swept bird head style grip, recoil is extremely easy to manage.
Here's a pic from when I first put the grip on. If you really want a pistol grip, this is the way to go. I'd say to keep that Winchester, and pick up a 500 Cruiser - they can be had for less than $300. The birds head grip was 30 bucks.
