If you shim them with a small washer or something of the sort, you will learn a whole new volcabulary when the shim drops alongside the spark plug and you have to figure out how to get it out since the plug socket will not go over the plug with shim between plug and plug well. If you are "lucky" enough to get socket over plug, then you must deal with near certainty than the shim will fall in the plug hole when you remove the plug.

Had to work better part of day fishing a washer out of plug well when I found the washer i had lost some time previously when removing the upper plenum. Was not happy to find it! Damn happy to finally recover it!