Welcome Motormouse. I'm a newbie here as well and I'm enjoying it and reckon you will too. You're a lucky barstard getting a bike in such great nick
. I raced a KX400 the same model back in 1976/1977 and have only good memories of it except for the lack of parts backup back then. I wouldn't doubt that it'd be easier to find bits today though.
I reckon twin shock KXs are not only amongst the prettiest Japanes bikes of the era as Graeme says, I also reckon they were the first Japanese bike that
felt European to ride. It's hard to single out the reason, it's just that they felt unlike the Elsinores, MX360 and DT1MX I'd previously raced. I went to Huskys after that and the transition was smother than I'd ever hoped for because the bikes felt like they came from the same mother! Good luck with the rest of the resto and keep us updated on it's progress. There aren't too many other Kwaka owners here so it'll be great to see it at CD6 and other events.