Once the cam has been fully installed into the block, double check that it sits behind the face of the block before installing the cam retaining plate. If the front face of the camshaft sits flush or in front of the face of the block, then the cam plug will need to be addressed. If this is the case, then the problem could be as simple as the cam plug being driven in too far or the wrong thickness cup plug being used.
Regarding installed camshaft end play, it’s always recommended to mic both the spacer and the cam retainer plate and insure that the spacer is 0.004”-0.006” thicker than the cam retainer plate. This will insure the aforementioned cam end play values. If the cam spacer is the same thickness or narrower than that of the cam retaining plate, then the cam shaft will bind when the cam gear is tightened to the camshaft.
And as has already been mentioned, any lack of cam end play can potentially break the cam retaining plate whether it’s a result of the cam plug being too far into the block or inadequate clearance at the cam gear. Using a belt sander on either the cam spacer or the retaining plate can fine tune the cam end play clearance values.
Here’s the link to the article that was recently published in the Y-Block Magazine.
Rear cam plug installation

Lorena, Texas (South of Waco)