What did you go for in the end, 40/65?
I had an e-mail back from gripper and the contents explained a lot to me. They were stating that they make them up with between 65 and 75lb/ft of preload, which on a car that makes 100lb/ft is pretty insane. That adequately explains why I have been experiencing the things that I have. They suggested re-building it with 40/65 ramp angles and with 20-30lb/ft preload, which I can appreciate will make the car behave VERY differently.
I think I will send them the 31V LSD unit, as there is no point in having the 30A version re-built as it will never be used. I will also more than likely go for a unit without speedo drive this time, as I am intending to use one of the ABS hubs as a pickup for an electronic speedo.
Now that I have heard the above, I am feeling all together more positive about going forward 
