Can't you just drill new holes in the shield if it doesn't line up with your pickguard? Any modifications that you make to the shield will be covered up by your pickguard, so it doesnt matter if it doesn't fit perfectly.
To be honest with you, i never saw the point of pickguard shields...
Just put copper foil over the control cavity and pickup area and you will be shielded just as well as with an aluminum shield.