Bifwynne.....I don't think you could just put a 3D armwand on your Classic tone arm base.... I would check with VPI in any case.
Also....the Atlas and Etna cartridges are fabulous, but in order to hear the nuances these cartridges are capable of providing, you rally need the most sophisticated of components. If you don't have access to these, a less expensive but wonderful cartridge will be more suitable.