Looking for some Differential advice

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.
I got fortunate with this one. It was given to me along with a Ford 2.3 and a bunch of other Ford stuff. It sat on the outside shelf three years covered up until I got to thinking about a T5 swap in Vixen, then I got it out and got some numbers off of it showing it is a world class V8 transmission. It's even the Tremec version....for whatever that's worth. lol