Gear choice

3.21 for sure. If you are indeed swapping to an AX-15 you'll want a taller rear end ratio as the 1st gear is very deep, iirc 3.6x:1 and 5th is not a very tall OD ratio at 0.79:1. @75slant6 has one in his Duster and I think he put 2.94s in his car to make 1st hear not useless.