Folks from COBB got back to me. The outer diameter for their 5mm conical spacer is 43mm http://www.cobbcycling.com/shop/accessories/5mm-top-caps. It won't be flushed with headtube!
update: stock conical spacer is 48mm in outside diameter not 45mm!
2013 Specialized Allez Race E5 OSBB (updated photos)
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