Seems hard to give an educated guess. Weight could vary some within the 'breed standard', then you have the unknown mix involved. Any dogs poundage can be up or down depending on diet, exercise, and how and what the owner fed longer term.
When we got our female G. S. pup the breeder said she should be 68-73 lbs as an adult, with ideal weight. That's rather exact, I'll see if we get there. She is just over 4 months and was about 32 lbs at the Vet the other day.