If your going to all this trouble, tear that diff out and get a posi unit from Quaife. http://www.quaifeamerica.com/differe.../diff_apps.htm
It's not cheap $1,700 but since your gonna be ***** deep, might as well go all the way.
Personally I would install the SRT6 gears in my 6 speed car, just to make 1st gear a little more useable for the street, then later on you can change the tire and rim diameter to something that is a little less expensive for Lo-pro tires.