Which Assos garment are you considering? The Lycra bottoms run a size small. The tops are at least the same from what I have heard, but the Uma jacket may run tighter. The roubaix knickers - an XL might fit you. Maybe. They really screwed up the sizing of their women's bib knickers and tights made from the heavier roubaix fabric. For some reason, they managed to size the same items for men just like the Lycra items.

Sarah at cbike.com is very good at women's Assos fit and they stock most items, but sell at typical retail prices.