Hi jds
Yeh there is a 2" step up to chassis mount. This is, Iam informed, to achieve the required driveline angles with min body mods when using the Datsun transmission and is suitable for most of the variants of Datsun sumps. The steering rack and track control arm dimensions are still in the same plane as the factory, however the 2" lift may result in a slight change in camber angle as it changes the "theoretical length of the strut ratio with control arm", this could be compensated for, with adjustable top mts or track control arm. The caster may be increased, depending on the type of anti roll bar used, but any increase would be in the "+ desirable direction".
As you correctly guessed, I didn’t build the xmember. I bought it years ago when I was going to do an SR20 conversion, but I picked up a 2.0 Mondeo cheap and the rest is history.