I don't safety wire these, I use elastic stop nuts and or double nut the bolts.
Never had a problem.
On the other hand, I have had, and seen on other 4 cylinder Lycomings, broken adjustment bars and a broken alternator mount.
If you drill a hole in the adjustment bar, do it as pictured. I would avoid drilling the beams of the bar adjacent to the slot.
The breaks of the adjustment bars I have seen were in line with the alternator bolt. You might consider a wide washer to distribute the load wider than the head of the bolt, and to hold the bar in the event that it breaks.
The alternator mount that was broken was a VAN's lightweight mount for Narrow Deck engine, so you probably will never see one of those.
This is an important area to inspect regularly, especially with today's electricity dependent aircraft (EFIS, Electronic ignitions, electronic injection etc).