best oil for cam breakin

The XE284 should have double springs - that means there is the main outer spring of round wire, pressed inside the dampener of flat wound wire, and inside of that is an entirely seperate smaller round wire spring. If that is what you have you need to make sure the inner springs were not installed on the heads and break the cam in with just the outer w/the dampener. If you ran the first cam with inners installed - that's why you lost a lobe. The cm is not that large.
I would recommend using the Not For Street use VR1 to break in the cam, or 14/40 fleet with a can of zink break in lube. Follow the procedure in regard to time and rpm and you should be golden. Once it's done - install the inner springs.