As far as I can tell (from measurements, checking for binding, rod ends in/out, pretty much every suggestion given above, etc... etc...) everything is pretty much equal.
It seems the best course of action is just to wait for the engine, put it in, and see if the final weighting effects it. (in terms of how it's balanced, obviously more weight = adjustment back up).
Thinking about it now, that does seem to make sense - I remember when doing the ride height on my cobra the rear shocks were really unevenly balanced before the engine was in, and then roughly evened out after the engine went in. So my initial assumption of engine in centre = no effect side/side in the front may not have been correct.
I doubt most people are scuttling around the car trying to set ride height before having their major componentry in, just so they can see wheelwell arch clearance, heh. What can I say, I'm special like that :drunk: