Bruce,
First, you don't have to have any impacts at all to have camber issues with older cars. The camber tends to go negative on strut-type front suspensions as a matter of age. A strut brace might have helped when the car was new, but in and of itself negative camber is not a bad thing, unless it's excessive. Camber also should not effect the track of the car, provided the toe is set evenly on both wheels. Volvo's specs that are loaded into most alignment machines tend to scrub the outside of the tires off over time. If memory serves, specs call for about .3 degrees total toe-in, when in fact .22 (.11 each wheel)is a much more realistic spec. See where your shop set the toe first. Get a printout if you can.
If you are getting a "pull", first thing is to check it on a 2-lane vs. a 4-lane(drive in the left lane and see if it tracks differently) road. Road crown can make a big difference in the way the car tracks, and the alignment shop may have set it to try to compensate for that.
Should the camber be negative by 1 degree or more, Volvo had a service bulletin many moons ago addressing the driving out of the bolt in the front of the strut plate. 10mm center to center on the bolt will give you approximately 1 degree change in the camber. Re-drill the hole in the strut plate and away you go. Many alignment shops won't do it because it is time consuming, and they don't want the liability of drilling holes in anything. It's really not a "hack" solution though.
Hope this helps