All our Gibson style, Martin style and Taylor style pickguards are made to standard (vintage) templates. These are available here for you to download and check. If printing them out, make sure they are printed full-size - some pdf and printing options default to a 'fit to page' value.
We also sell 3M 467 adhesive film. This is the adhesive used by all the major US manufacturers and is much stickier than that provided with some cheap pickguards. When fitting, make sure that you roll it on from one edge to another, avoiding air bubbles (though they can usually be sorted out by pricking with a pin if necessary). And by the way we recommend Goo Gone™ if you need to remove old adhesive - it's readily available on EBay, etc.Pickguard fitting tip