I came across this ad on Ebay - looks as if the engine (minus supercharger) might still be available as well as other bits and pieces.
http://www.ebay.co.uk/itm/LANCIA-BETA-Trevi-Volumex-en-pieces/111964705736Translation of ad:
Hello. Many pieces have already been sold : Volumex , carburetor , headlights, steering wheel, electric beam BC , and others are not in good condition ( the gearbox with hole in housing ) .
Make your request, and I'll tell you if it's available , what state and at what price.
The car is being dismantled and will go to breakage.
Answer in English , Deutsch, Italiano.