Steering rack and steering arms don't have to be level.
I think first you need to establish whether you actually have bump steer or not.
Bump steer is movement of the wheel in or out during movement of suspension and produces a car which is unstable over bumps.
I'm surprised that he didn't check for you. An easy way is to simply remove the coil spring from the damper and refit the damper. With car jacked up and wheel removed, use a G clamp or similar to attach a long piece of metal or a brush handle to the disc. With wheels in a straight ahead mode, lift the suspension through its normal travel and watch the end of the length of metal. The length will exaggerate any movement. It is difficult sometimes to get no movement, but it can be reduced and or confined to part of the travel least used, by moving steering rack. Do this both sides (They can be different).
As an aside, excessive slope of the steering arm may not be good as it may cause binding of the track rod end and potentially cause damage. Whilst you have the spring off move the suspension through its normal travel and at regular intervals move the wheels from lock to lock and check for any stiffness or binding.
Paul Richards
Joint AO - L.A.D.S. (Lancashire and District Sevens)
Growing old is compulsory - Growing up is optional