Honda-SOHC

Stunning!

Wonder what the PO (presumably in the US) would make of it now?

I agree, good call on the wheels. They should clean up or refurbish nicely.

I noticed a wiring loom was on your list of parts you needed.
If you strip it off the bike and think it is salvageable there are threads on here about repairing them including cleaning muck off in the dishwasher.
Steve at 400fourbits (http://www.400fourbits.co.uk/) says he has one for spares with some good connectors if needed to splice in to the original, but new connectors also seem to be available.
DS want £150 for a new one so worth a try to salvage the one you have.

Motad is a member on this forum, Ian

Ian was a member but he retired from Motad in August 2015.
http://www.sohc.co.uk/index.php?action=profile;area=showposts;u=13680

Pretty sure they are aftermarket, I have seen similar ones fitted before to 400's but don't know the make (maybe ERA?).

.... I bought a set for my 400 they are made by A.R.E.

I was very close. Right letters, just wrong order!

A bit further afield there is a guy in Leicester I have seen recommended on other forums but never used.
His name is Robert Coley and he calls his company Leicester Wheel & Brake Restoration.
I don't know what services he offers; I had a quote for wheel building but then didn't go that route.
Contactable on bobcoley1@hotmail.com.

Pretty sure they are aftermarket, I have seen similar ones fitted before to 400's but don't know the make (maybe ERA?).
There is probably a maker's name on a spoke or rim somewhere.
Think Yamaha ones are seven spoke, not six.
There is probably a market for these if you want to get rid of them, or keep them as a period accessory - depends on how original you plan to go.
Also clocks look like Superdream.

Wheels required then !

May be able to help with a front one, or just a hub if you want to rebuild with a new rim - it depends what you need.
From your earlier post does that mean that you have cast wheels?