360 crank has a large oil seal groove

I just noticed that the crank on my 360 has a very significant groove where the front oil seal sits. (crank is out and almost ready for the machine shop to be rebuilt) It looks like it was actually machined that way. Is this normal? Yes it's the first time I have ever seen a 360 crank out of the engine.......guess that's why I'm asking . I don't have any calipers to give any dimensions either. Maybe I should get some of those.......thanks