You are looking at a 1 inch increase in depth, but it’s not just that, you have to take into account the excursion (X-max) of the new driver. I don’t know if you have a speaker grill or if it is a grill-less installation but you should take that into account as well. You might be able to attain the depth of installation with a ring spacer but find out the excursion of the new driver might be hitting the grill or the OEM ST sub-cover.
You can make the spacer ring out of plywood with a jig-saw, using the new speaker as a template. Draw the outside diameter of the new driver, the new holes, then find a plate or circumference that will not interfere with the new driver’s rubber/foam surround for the inside diameter and you should be OK.