OK, thanks for the replies - I have it filled up now and after a bit of carb fettling it starts easily and I've had it up to temperature and amazingly..... no leaks, oil or water ! Well, almost, I could see that as soon as I started to put oil in, the rocker cover gasket wasn't holding - I had refitted the old gasket as the cork one I got from Robsport was nowhere near the right size, far too big. No matter, I just cleaned the old one and used a thin line of silicone on both sides which gave a perfect seal.
A few electrical issues, lights not popping up and down correctly, brake lights stuck on, wipers don't turn off.... but it's not a problem, I can work through those one by one.
The only mechanical issue so far is the viscous coupling rattling away. There is play where it locates on the shaft, which I presume means the bearing is gone and I guess the fix is to press it off the shaft and fit a replacement - do I just need a new viscous coupling and tolerance ring for this job ( oh, and a press) ?
Bleeding the brakes was a bleedin' trauma ! Not so bad the front but the rear, sheesh !! I ended up making an adapter to fit in place of the reservoir cap in true Blue Peter style
from the top of an old Fairy Liquid bottle, a short length of plastic tube (to fit over the spout of the FL bottle cap) and a rubber washer to seal. This meant I was able to connect to my compressor (set on a VERY low pressure) and with the wife holding the brake pedal down, a gentle constant pressure pushed the fresh fluid all the way through the rear brake lines and out of the bleed screw. There's a reasonable pedal now but as it's nowhere near ready for the open road yet I'll give it a final commissioning nearer the time
cheers
Dan