Peter
They used a version of the Abarth 16 valve twin-cam cylinder head, mated to the Lancia block. It's all in 'Twin-Cam Italia' by Phil Ward. I could try to scan the pages if you can't get hold of a copy.
Neil
Hi Neil
Ah, I am away in France and hence no access to my books and could not remember if any of the few Beta books I have mentioned it. I will look it up when I get back, many thanks for letting me know.
Peter