Any pictures I can find of your motor show the prop being white.
Evinrude had some strange names for their paint colours. The cover was Charcoal Gray with Aqua trim. The lower section was Light Gray so I’m suspecting your white prop was originally called Aqua to match the cover trim.
Thank’s Mumbles. I thought it was most likely white but I wasn’t sure. Is that a picture of your motor? It sure is a beauty. I think the 1957 Lark is the prettyist motor Evinrude ever produced. I am in the process of painting mine and I want to get the colors correct.