Thanks for your sypathies chaps.
There are a couple of sources online that may sell the right one, they are different to the later 1900/2000 gasket I have in the garage

(typical!).
Emails have gone and if that fails I know the guy who runs the Matta register (yes there is such a thing!!).
Will be doing the work myself

Understand these old chain driven Twincam engines are easy to work on....they need to be as I've never done a headgasket
wrinx