I think you're underestimating the jump down from 58 to 55 cm.
I think 57 is my size now that I tried the F.Moser for a longer ride. Still its 120mm stem is too long.
Maybe you'll have to invest in a new, shorter stem?
http://www.ebay.co.uk/itm/F-MOSER-Engraved-3ttt-RECORD-Stem-size-90mm-clamp-25-6mm-quill-22-2mm-Silver-/121697112192?pt=LH_DefaultDomain_0&hash=item1c55b69080
@anidel started
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I think you're underestimating the jump down from 58 to 55 cm.