Thanks Coolhand. :)
Well because the shocks are so long, I've had to do some custom mounting. The only way to mount them without increasing weight too much or mess up the CG was to custom-mount them like this:

...which probably explains why the damping feels so stiff with 70WT. But hopefully with the lighter oil, it will be better, and it should be quite progressive with the shallow angle. The rear arms are longer, so the shocks are positioned further out. The springs seem fine too, the whites look to be just right at the front with "arms level" ride-height. I haven't been able to mount the rears yet as I needed to orer some more long hinge-pins.I just hope the force of the shocks won't bend them!
Thanks for your help. :D