Lee,
with my basket machined enough to clear the outer cover, I recall when I initially reassembled; the plates were not under any pressure and even rattled, so I had to get an extra plate. Once I had contact between the end plate and the basket inner through the plates I was fine. But I can't tell you readily how many plates that resulted in.
Just that in my case I didnt need to modify the inner at all. If I wanted to reduce the number of plates from the number I ended up with something would have had to be changed.
In my case it was very clear it wouldnt work as initially assembled and fitting a further plate was the easiest option.
There was certainly no middle point where the spring tension came into play.
The (6) sprung bolts on mine are done up tight, unlike a typical british clutch where tension is variable with a nut on a stud.
Sounds like you need to mock assemble. As mine's in the bike I'm not readily able to confirm heights or plate numbers.
Tim
