Looking for some Differential advice

She's gettin 4.11s in a Ford 9" with 215 70 14s and a World Class Ford T5 transmission.
that should work VERY nicely. Good first gear in the trans, but with the 4.11s its gonna be short. The fifth overdrive will tame the 4.11s down a bunch, but not so low that you will have to downshift all the time. Like the tall 14s, too.
Loved my T5, and it wasn't even a world class.