Fox always used different barrel weights.

The weight number (1-4) was stamped on the tube when in its raw state.

It's very common for the weight number to be struck off during finishing as Mr. Newbern has stated.

The earlier guns exhibited a much higher level of filing and polishing (even in the unseen areas) than the later guns, which is one reason that the later guns more often retain their weight markings.

As far as I am aware all pre-Utica As had flat-topped checkering.

The early guns had much more (and more careful) hand finishing than the later guns. This also applies to the inletting.

The odds of finding another forend that will fit both your iron and the barrel contours (without rework) are pretty slim.

Perhaps the best thing to do is nothing and let the gun stand on its own merits.