Boxer Rebellion

Hey Guys - I purchased a set of used Elgin Super C2 Cams from a shop in the northeast a few months ago, for use on my '87 Carrera. My engine builder is getting around to installing them now and noticed that the nose of the camshaft which interfaces with the drive sprocket has been milled or tapered such that there is no longer a machine fit between the drive sprocket and the camshaft, but rather a .020" gap - resulting in a sloppy fit. 2 questions:

1. Why would cams be milled here?
2. Can anyone recommend a solution?

These cams were installed on a 964 or 993 engine as they have the power steering drive. I'm a bit confused because 911s from 1970 through 1998 all use the same drive sprocket.

Thanks for your help!