Shoebox Brake Drum replacement

[Rocket455]

I bought new drums from Dennis Carpenter. I received what was pictured in the catalog. But they don't fit. There is an extra lip on the new drum that interferes with a piece of the backing plate. My old drum didn't have this lip. It wouldn't be very hard to cut this piece off of the backing plate. But I don't want to start cutting stuff until I know what the deal is.

Is this the way it's supposed to be?
Did I get the wrong part?
I would think that if I was supposed to cut the backing plate they would have had some kind of note in the catalog or in the box or something.

My car is a 1950 2 door couple. Original V8 car with overdrive.


I have attached to this post a picture of the new drum, my old drum, my finger pointing at the piece of the backing plate that is in the way. And also my hand holding the lip on the new drum that I'm talking about. Hopefully, that makes sense.
Thanks in advance!