Raising the ride height won't eliminate the interference. It will only make contact less frequent. It will also cause worse handling and braking, and it looks dorky.
Lift blocks only work where the axle housing sits under the leaf spring.
If you're set on raising the ride height, there is a set of leaf springs out there that is claimed to give you a one-inch rise. The claimed purpose is to make the rear match the front, which in OE form sits higher. I can't recall where I've seen these, but it was in one of those full page ads in Mustang & Fords, from Laurel or Virginia Mustang or Dallas. Not Mustangs Plus, although I wouldn't be surprised if M+ has them too.
The other ways to cure rear wheel interference are to roll the fender lips, replace the rims with a set with greater backspacing (it's always easier to buy too much backspacing and reduce it with a spacer, than it is to add backspacing, which is impossible short of machining the mounting surface), or shorten the axle tubes and shafts (way, way too expensive).