I've managed to acquire a reed block from Steve Goode and it fits my Jumbo; article here . There are the recommended carb settings the in original SWM document for with and without the block but interested in knowing other peoples settings (that work) are

I have a Jumbo with reed.

I use standard jets and needle in third slot (richer)

works for me but the timing is critical!

good point on the timing; to date I've done it a little by random, so any suggestions on timing points welcome

I time my bikes to standard then whilst practicing advance and then retard a little.

Testing this way means all things are equal and the effect of timing are evident.

Obviously dont ride in water!!!!!!

so, I've following Martin's advice from an old email I had and rotated the stator plate clockwise by about 2mm; retarded the timing. Pulls like a horse now, and with the reed block, the pickup from pilot->main a lot better. Need to sort the exhaust etc but all going well