It looks like this beautiful engine will be back in limited production again - not from Porsche but from Capricorn Automotive GmbH of Germany. The expensive Hirth multi-piece crankshaft with roller bearing crankpins has been replaced with a single piece forged crank with conventional pressure lubricated journal bearings. Otherwise, the engine is a virtual duplicate of the original. Here is a link to their site:
http://www.capricorngroup.net/fileadmin/files/images/capricorn_Anzeige_Motorsport_UK.pdf