The stack is only about 3/4" higher on the 61cm.

Is the stem max height on the fork on the 58? Can they flip it or exchange it?

I just feel that 61cm is way to big for you,even though the handlebars are higher.
And you like how the 58cm feels.I'm kind of surprise they are suggesting the 61.
Also check out other LBS in your area.good luck