100 for 56, 110 for 58, 120 for 60 according to a Specialized chart I have.
I think you could go a bout it several ways:
Problem - in my case the stock geometry makes the bike too tall so I need to solve that problem. I also have disabilities that I have to work around.
Conceptual - I'm and x and a y so I need a special frame, though the frames I have riden don't give me any apparent problems. But maybe one is compensating with the stem etc... and not getting to the level of fit one otherwise might.
My feeling is that fit is important and complex and probably isn't easily solved by any one stab at it, so if you don't start working on it, you probably won't get the actual answer. Working on it requires trying some tailored frames, if that is possible.
I have worked with fit issues around golf and now cycling. I have a fairly dim view of even well known and respected systems. To really fit a person properly can require the knowledge of a coach, builder, and fitting specialist. Few people have the tripple competency. But good results can come up relatively quickly with a trial an eror approach though it is unaffordable for most unless they have access to a lot of product.