AMC clutch on lay down box replacing early Norton unit

I did this on my 1956 Dommie 99 several years ago and it was a great improvement, but maybe because the replacement AMC unit was in better condition than the original clutch. No issues recalled, dispensed with the "mushroom" and tailored a silver steel pushrod.  I recall ball ending the clutch end of the rod before hardening and attempting a corresponding hollow in the adjusting screw which was hard work. Possible advantages other than more readily available spares: clutch adjustment now available on both sides and the adjustable springs on the AMC allow more accurate setup.

.. is that I prefer the older style clutch as the mushroom virtually guarantees a straight lift.

Think I read somewhere of a clutch mushroom fitted with roller bearings, laid out radially.
I guess the intention was to reduce friction and thereby somehow (magically!) "improve" clutch actuation. 
Except of course there's some additional weight, so perhaps any gains must have been minimal, to say the least... 

Is that the cylinder that wraps round the clutch?  It's supposed to be there to reduce (prevent?) oil contaminating the clutch cork inserts.  But surely it only slows down the inevitable?  It will work without it anyway.  I suspect it's a "nice to have" rather than "of vital importance".
What's the wire circlip for?  Perhaps just for convenience during factory assembly?  It doesn't do anything when it's on the bike.

A 5 speed modified laydown (Arrgårdh) fitted in -63. Had a 3 part pushrod and some balls and rollers between. Was a common a practice to have 2 pieces  with a 6mm ball bearing.

Try Dave Coates for any Clutch parts 
Dan 

Regarding numbers of plates.  Standard as used on 16H and described in WD 16H Manual is "six plain steel plates and 5 steel plates with ferodo linings". The WD manual can be downloaded free from several sites including wdnorton.nl
Inters had only 3 friction plates.  Probably  because they raced with a dry open primary and chain lubrication by drip feed, so they saved weight.
The early basket of course has friction inserts.  I guess they changed with AMC design for production reasons?

I can't find enough published stuff to compare...!  Prewar parts lists have tiny pictures.

The biggest changes were of course by swapping the plain plates (including the back plate) for friction plates, and changing the friction plates (including the basket) for plain plates.  And then by deleting the screw release design with the lever used in the AMC box - which is much tidier but pretty crude really.  The older design is easier to adjust.  The three screws are simply tightened solid.  And as long as the three springs are close to the same length, the mushroom makes sure the clutch lifts cleanly. The AMC one just wobbles about on a single point.  And the old lever is easy to adjust and it's not easy to put them together wrong.  Not like the AMC where the lever is mounted on a ring which can be twisted out of line.