Let's have a closer look at the camshaft seals, and the concept of seating them deeper to solve oil leaks.
This pic, from Jim's overhaul thread, post #4.
http://www.xs650.com/threads/xs650-top-end-buildup.52041/#post-548735
Shows that the preferred oil seal seating depth is to have the seal's backside be flush/even with the backside of the cam endcovers.
The question is: If the oil seal is seated deeper, will its OD contact the bearing cage?
Here's an oil seal, 40x25x5mm, and a cam bearing.
The cam bearing's outer race ID is 39.5mm, just slightly smaller than the seal's 40mm OD.
Placed atop the bearing, and pressed down, the oil seal will NOT contact the bearing cage.
What DOES make significant contact is the inner lip's backside to the bearing's inner race.
Measuring the clearance depth of the bearing cage shows 0.5mm (0.020").
Another view, showing the backside of the oil seal, reveals a slight chamfer of its edge, and a slight chamfer of the bearing's outer race ID.
Even with these chamfers, I was not able to press the oil seal deeply enuff to contact the bearing cage.
What this means, based on this test of 'my' parts, is that camshaft oil seals can be safely pressed a bit deeper, if need be, without concern for contact/rubbing on the bearing cage.
However, the seal's inner lip backside WILL be in rubbing contact with the bearing inner race. It would be prudent to ensure that there's a bit of lube on that contact face during assembly.
Update 10/6/2019
Member Wulfbyte encountered seal to bearing cage contact in this post.
Post #6499.
http://www.xs650.com/threads/what-have-you-done-to-your-xs-today.32082/page-325#post-614595