These are the very illusive factory 906 Twin-plug racing heads https://pbase.com/9146gt/image/37944260 The heads feature large 45mm intake ports https://pbase.com/9146gt/image/39255414, 39mm exhaust ports https://pbase.com/9146gt/image/39255426 and valves https://pbase.com/9146gt/image/39255416 that are nothing less smaller. The Porsche 906 racing heads come in a twin-plug configuration and use the smaller 12mm competition spark plugs https://pbase.com/9146gt/image/23654089

The heads are almost done https://pbase.com/9146gt/image/99979821, the last step in the restoration is lapping valve seats, installing the correct factory ATE valves, new springs and retainers and these will be done. More photos to follow.