The ackerman effect is not a worry, it`s a function of the steering arm angle and length.
The important thing is to find a rack with the same length between the centers of the inner track rod joints as the distance between the bottom suspension arm inner pivot points.
Failure to achieve this will result in terrible bump-steer and roll- steer effects.
BTDT, not on a Volvo, the principles are the same regardless of make.

Colin.