mazdatweaker_2
+1y
It would help if someone could post a picture or two of a non-damaged head with the journals exposed for point of view. I would if I had a head available.
The problem isn't so much the journals, but the oil galley holes getting blocked from metal smear from the prior damage and then they block off oil flow to the replacement cam if they aren't drilled out. The shavings / filings are another issue entirely. Time with a slow speed drill, some grease, and hope that the bit doesn't break off.
All of this is doable but for many the easiest route is to replace the head if the engine is otherwise ok.