need some help need a template

I plan to run kelsey hayes 15" steelies 7" up front 8" in back. I have a set of 15x8 KH chevy suburban rallye wheels i plan on using the hoops from, and jig welding in the mopar centers. Paint em all body color and add plymouth 67/68 dog dish caps.

Since i am running the larger bolt pattern, I am going to get a donut spare from a late model mustang or crown vic that has roughly the same diameter tire or close to it for my rear tires. It should fit in the spare tire well diameter wise, and should be narrow enough that the cover will fit flat on the trunk floor. Not too concerned with originality on the spare as i am running cordoba brakes, and a 14" wheel will not clear the brakes.

Most people forget these cars came usually with a 14 x 4.5" or 14 x 5" steel rim. Anything wider than this doesnt allow the spare tire cover panel to sit flat against the trunk floor.