Hello Chris,
1. How many rivets are required to fix the door top chrome in position and how are they spaced?
Four - see pictures below for spacing. The spacing in the pictures are incremental starting from the very front most hole. The very front most hole uses a screw to secure the front end of the chrome moulding, not a rivet clip.
2. How many screws are required to fix the same door top chrome in position and where is it/they located?
One - at the very front most hole.
3. Are there supposed to be one/two or no small screws in the upper rear part of the door frame holding the window frame in position (in addition to the brackets to front and rear of the base of the door frame)? My car has these but I'm not convinced they are original, or required given the frame fixings to the upper and lower parts of the door.
Yes, there should be two screws - see the two attached pictures below. The Green Sands car is a totally unmolested car. The screws for the Red car have not yet been been finally assembled.
4. I can't seem to get hold of the special rivets ("cup and rivet" - BD26706/3) from the usual suppliers - any ideas as to where these can be purchased?
Not sure - SNG Barratt are showing them as no longer made - XK Unlimited show them as an available part, but nil stock.
Regards,
Bill