Thanks for the photos, that helps a lot! I can see that neither is very close to the correct profile, the front of the F7's nose is too vertical, while the windshields of the F3 have too much of a "California chopped-top" look to suit me, the top of the diaphragm has a funky cathedral looking arch, and the rounded curves on the nose don't look quite right to me either. It does look more like the Lionel she'll, but I don't think Lionel got it right either.
I'm sure the coming Atlas F7 will be better (but will I be able to afford it?), and probably the MTH Premiere is better too (but not the Rugged Rails version, it's just too small). As I remember, the Roco/Atlas F9 from the seventies wasn't too bad, except that it was an F9 rather than an F7, the sideframes broke off easily, the axle gears were prone to splitting, and making it operate on 3-rail track was a problem.
Do the currently available Williams F7's that are sold in sets of two A units (one powered & one dummy, have knuckle couplers on both ends of both units, or are they connected with a drawbar between them? The catalog jus says "working front couplers", and the optional B-unit doesn't mention couplers, which makes me wonder if it has draw bars as well.
Thanks again for the photos,
Bill in FtL