A little more searching and I came across this thread.
http://www.early911sregistry.org/forum/showthread.php?t=11540&page=2&highlight=dash+switches
Soterik would be your man to ask with 5 '67S's I think he will give you the answer you need. He does state in the thread however that in '67 the Webasto heater was standard. So that may be your answer. Could the heater have been removed?
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'73 914 2.0, '74 911 Coupe, '74 911 Targa
'78 924, '84 944, '86 944 Turbo, '84 911 Coupe
'84 944 (current), '96 993 Coupe (current)
'73 911T Coupe (current)
'88 930S M505 (current)
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