Hi and Welcome John.
Humber, Cargo, Chassis # 6310021, original engine #13601, ARN 105 691
"declared for disposal list 5B/VSD/B27 21/5/69 "
I think the 5B is "5 Base", sure I will be corrected otherwise, as for the VSD/B27 no idea, possibly the sale tender/contract as there are other trucks with identical info.
The tracta boots are an awkward job to replace, they do come up for sale on occasion, but will perish shortly after fitting. Dave Mills is the man to speak to, he has pioneered the design of an easyfit replacement.
Plugs (RSN13P) come up on Ebay quite often, or available ( as Richard F. suggests) from Tim Vibert;
http://www.timvibert.com.au/
Tim will most likely have leads, fuel pump, and possibly both sets of points.
Points can be replaced with electric ignition, much simpler and more reliable, but not cheap.
(worth every cent though!!)
NB The fuel pump is not the same as the one used on the B40 (Champ) motor, one of the few parts not common through the "B" Range.
Pioneer brackets etc, easy enough to fabricate, yell out if you need pics, or you can probably buy used from Altmanns in Stawell,
Is this a restoration, or a get it up and running project?
As for questions, ask away.
Rich.