This is an old thread, but I do not see recent posts on the subject.
I was looking at posts on playfield angle where it seems that for Gottlieb EMs, the "factory recommended" angle measured on the playfield was 3.5% (although some may prefer a steeper angle). In contrast, the more modern games are set at 6-7%, all with the understanding people can pick what they prefer.
Is there any list somewhere that lists the recommended angles for machines? For example, for an early Bally SS, would the suggested angle be 6%? I would be curious to know the recommended angles of all of my machines.