looks to be correct number there Bill.
this side of the pond we buy them here:
http://www.murphskits.com/catalog/product_info.php?cPath=1_97&products_id=52When you reassemble the bike, and replace the fork fluid, the fluid level should be measured without the springs, and it should be 355mm from the top of the fork tube
with the forks extended (place a block under the engine to get tire off ground)
Also, you will still retain the hat shaped washer to be used on top of those new springs, but I believe you will need to remove the steel tubular spacer from the stackup at the time of replacement.
the original o rings for the crossover tubes should easily seal the oil in, and you won't be adding any air.