right, sunday morning update.....
have completely fed the new chain in and disconnected it from the old one.
I then turned the engine over till the O/T mark on the crank lined up with the pin on the crankcase (found the pin at last...

) like this:
At the same time the O/T mark is aligned, the rotor arm is pointing here - although its not pointing directly at it its pretty close? Is that ok?: (i also found the correct notch-cheers chris!)
Also, when I put the distributor cap back on the rotor arm lines up (roughly) with lead number 1
Does this all look ok for far?
I now reinstall the cams (dots aligned) and connect the chain yes? Then top guide rail then tensioner?
Phew, this is tough going......
thanks everone.