It does look like a 66 body. My best guess is your machine started out as a treadle machine and Great Eastern refurbished it in the 1940s adding the motor, modern hand wheel and newer style stitch selector with their own cover in the process. I have a 1948 Singer 66 and it's stitch selector and bobbin winder are different than what's on your machine. It could be your whole stitch selector is aftermarket, Singer stitch selectors and covers don't look like that.
Neat find.
Rodney