my z has full suspention (all the same as a 240) and i take it to one of the newer tire kingdoms around hear is west palm cus they have the alignment machines that are built into the ground  so thier are no clearance issues and they have np going and grabing 2 adjustable wrenches and working with all the parts on my car. on top of that its all digital so at the end i get a full print out of all the specs for the whole car
seems to me like the people you took it to had no clue what they are talking about or are aligning your car with a string and a rock for them to say its harder with a new fully adjustable suspention.......