what about mr old Honda spares? David Silver http://www.davidsilverspares.co.uk/parts/by-model/, they take Honda UK spares for bikes over 20 years old and buy them back off him when they get an order, also http://www.cmsnl.com/honda_model8286/ in Holland, but ask them about availability as I had to wait for back order 6 weeks when I ordered online for a customer.
http://www.bike-parts-honda.com/honda/model/CB/450.html both the last two have schematic parts books which are a great help, if you find something , part number search on ebay, may bring something cheaper especially on ebay usa, no worrys buying from there as its all covered, usually cheaper despite postage charges. I did a Honda atc 3 wheel and the sprockets and brake cables were cheaper than a UK sprocket!!
