Welcome along David. Looks as if the bike has had some changes and improvements. A later tasty twin leading shoe front brake and possibly a later front mudguard. My guess is the fork sliders are also non standard and from the later unit range to match the brake, and you will be familiar with these.
Neutral is always a bit hit and miss at standstill, it will usually click in easily if selected as you come to a halt. Clutch drag is the usual cause. Kickstart quadrant and return spring come out of the box with the outer gearbox cover, all well documented on the Forum. Early quadrants can be moved round on the kickstart shaft splines. Later types are fixed.
At this stage with an unknown engine I reckon its better keep off detergent type oils, so any sludge stays in place. After a full strip down, modern oils and a filter on the return oil line is the way to go. Expect some internals not to be standard, I have the feeling time has been spent on what's inside rather than external bling. The bad news is that just like the A65 the bike is built around the sludge trap. On an early crank an example is in the palm of your hand. Yes, it's air, or rather simple oilway drillings in the crank and to clean these requires a nut and bolt teardown. You know this, other innocents have no idea. Later crank is considerably more complicated to clean.
Looks a good useable machine. Hammer and Chisel maintenance compared to the Kwakker.
Swarfy