Duster front ride height

Tire height and front ride height will not affect your driveline angles. Those angles are fixed; determned by your engine/transmission mounting, and the spring perches in the rear. The only way to change your angles (within reason) is by using angle shims between the perches and the spring (or by radically altering your static rear height, but you have that established)- which tilts the pinion one way or the other. The angle is the relationship between the output shaft of your transmission and the pinion (input) of your rear end, not either's relationship to the ground- which is what you're doing by changing the front ride height. Front ride height can affect your launch, and you can play around with that; but it is not going to affect your driveline angles to any measurable degree. So go ahead and measure & order your driveshaft.
Your front ride height you'll just have to experiment with to see what ultimately works best for you, but I suspect those 235 60 15s are going to need a bunch of clearance in front, they're going to be really tight and you may have some clearance issues to deal with, especially if you want to keep it low to get max travel.