Which longacre for bump steer

IDK
But all you need is to measure the toe-change with ever changing front ride height from full down to full up, or at least the middle 60% or so.

The toe changes with the camber change, that automatically changes as the control arms move thru their arcs. And the camber change is because the control arms are of different lengths.
So if the castor/ camber has already been set, then all you need is to measure the toe-change. And all you need for that is a tape measure, and something to lock the steering wheel in place.
But sometimes the cross-camber is doing a little dance too and you gotsto fix that first.This can happen if the cross-caster is messed up, or if the car is not going up/down level. Sometimes you have to fix the back of the car first, if the springs are not of the same rate, or if for some reason the back is not level, or if it changes it's cross-height during the test.So be careful to not end up chasing your tail!

When I did mine, I had to jack the rear up, remove the wheels, reset the ride-height and put blocking under the front spring perches, to ensure the rear stayed at a constant height and remained side-to-side level.

I was fortunate in that I was an alignment tech at the time and so I spent the day on the rack.