Very interesting, do you have any more photos? Hard to tell but the flyballs don't look Weeden and if you look at the frame from the side it is different than the link posted of the No.49, yet the frame has many similarities.
I have a couple of these engines but they are still packed away so can't check them. As an aside one of them was missing the cylinder and was listed upside down as part of a cast iron cart.😀