GB is correct.
The museum car isn´t the 1970 Le Mans winner, although the Porsche factory contributed a lot to this urban myth. The very museum car spent its years serving as a VIP Taxi on the Weissach test track under the capable hands of Hubert Mimler, by then "Werkstattmeister" of Weissach´s racing workshop.
On a sidenote, even as the factory admits, tracing back the history of many original 917 chassis is very difficult nowadays for a very simple reason: At the time between 1969 and 1971 Porsche only had five sets of customs documents with one Chassis Nr. in each set of documents for a fleet of about twenty 917´s coming to the factory for repairs, maintenance etc. So therefore, in order to avoid trouble at the borders, they simply changed the chassis Nr. plate on the cars leaving the workshop to keep the cars compliant with the customs documents accompanying them.
Best,
Marcus