Cascade at bittering shouldn't make much of a difference, but NB instead of cascade at Aroma/finishing will make a differnce. NB, IMHO is a very clean yet unique hop. You won't get the spicy/citrusy aroma from NB like you would from cascade. But the good news is, that for that particular beer, the flavor impact should be minimal. If anything, I bet it would be strangely delicious! (Ok, I'm biased b/c I really like NB).