Frightful- I'm going to have to go with Troublemaker on this one and say no to the completed build. Sorry, but he is right in what he said.
As for the Sherman, I don't really know much about them, but I thought they were a later war tank, replacing things like the Lee and Grant tanks in 1943-ish. But like I said, I really don't know that much about tanks. So the way I see it, if you or someone else can reasonably prove that Shermans were around in 42 and you make an effort to make yours look like it would have then, I call it good!
Thanks