Yes, you can put a scope on a Tracker II, but you will need to have it drilled and tapped before you can do that.
I set out on a project much like yours a couple of years ago, I started out with the 20 gauge Tracker II. Before I started out on the project I spent some time with a set of micrometers measuring barrel diameter, chamber wall thickness, etc. I determined that the 20 gauge ultra slug (which was drilled and tapped) had the same chamber wall thickness as a 20 gauge Tracker II (which was not drilled and tapped), therefore I saw no reason why I couldn't drill and tap it. So I did.
The end result is a lightweight 20 gauge slug gun that will group Remington Copper sabots into about 1 1/2" at 100 yards.
Here's a picture of my finished hunting rig. You can ignore the deer in the background if you wish :wink:
http://www.graybeardoutdoors.com/phpbb2/album_pic.php?pic_id=390