I have standard (not non-ghosting) LEDs in some select inserts of my BK, there is a tiny bit of ghosting on a couple of them but so slight I don't really notice it unless the room is dark and I really stare at them, so I left them in. But if the entire machine was converted I guess some lamps might ghost worse than others depending on where they are in the lamp matrix, and/or more noticeable because they are ghosting from another lamp that flashes a lot. For a whole machine I think I would go with non-ghosting on the feature lamps.

I don't have firsthand experience but I think gdonovan was one who has said you do not need non-ghosting LEDs for Williams of this era.

My Blackout has cheap retro led from Comet and they do not ghost in any of the inserts. Neither does my Sorcerer.