unfortunately Specialized frames are a bit tricky, because they come in several versions.
If your Shiv has an aluminum BB shell it's a standard BB30 and you can use the FSA BB30 Megaexo adaptor. The frame is 68mm wide at the bottom bracket. (http://www.power2max.com/...es/fsa-megaexo-bb30/
If it has a carbon shell the frame is 61.5mm wide at the bottom bracket and you need the FSA adapter for OSBB. Unfortunately we don't have it and it's not something that is easily found.
If it's within your budget I would highly recommend the Type S FSA Gossamer BB386EVO (http://www.power2max.com/...er-meter-and-cranks/
It's the most affordable Type S at $1049 with cranks and fits straight in the bottom bracket. It's also very future proof as it's fully compatible with BSA, BB30, PF30, BBRight, BB86 and BB386EVO. And if you want to go lighter in the future you will be able to switch the crank arms to the K-Force Light BB386EVO.
I hope this helps,
official power meter of Movistar Team