Don't worry about it. You don't need 100% pristine metal to achieve a good polish. It might take a little more time if it isn't but it is not impossible. With enough work even deep scratches can be polished out. My QB stuff arrived with a surface that would leave it very simple to polish.
RV-8 with the Showplanes Fastback conversion
Emp completed except for glass work
Wings completed except for bottom skin and glass work