Looking at the Specialized site, I see that they do offer the ruby comp in both 54 and 56cm sizes. The 54 seemed a bit small for me, and I am your exact height and pubic bone height. You should at least try a 56cm as well if you are going to shell out that kind of money. Get the LBS to check out your leg/knee positions in particular. You do NOT want knee pain and problems due to not being able to straighten your leg enough while riding.
Another note- the Specialized "Roubaix" is a man's bike and I notice that the top tube length is substancially longer for the very same size bike compared to the Ruby comp women's bike they make. So if you are also proportioned like me you might want to consider avoiding that longer reach on their man's Roubaix bike. I have a non women's specific Rivendell and I've had to do some tweaking to make the reach more comfortable, and it may well be impossible to get it perfect.