How should my duster handle

Alignment spec's are for straight ahead at factory ride height.
The assumption is that, by the factory design, the alignment will then also be correct for all other turning angles and suspension heights.
But if your guy did not set the ride height to factory, then ONLY your straight-ahead alignment will be correct.
Furthermore, if the back end has been altered, this will affect the front end.
The lesson here is that the factory-type alignments only work on factory original cars, at the factory specified ride-heights..

therefore; if your car; wanders, pulls, seems nervous, self-steers on bumps, or heaven forbid squeals the tires in normal turns, the alignment will need to be re-spec'd.