Deploying new Exchange VMs and migrating your mailboxes is usually the recommended approach instead of trying to P2V Exchange into a virtual machine. But going from Exchange 2007 to 2013 is not a trivial upgrade as the architecture of Exchange 2013 is significantly different than Exchange 2007. For example, there is no such thing as an SCC in the way that it is done in Exchange 2007. There are no shared disk clustering options at all.
I'll include some links to best practices for Exchange on vSphere and I think those can help you with some of the details on how to properly design and size Exchange on vSphere. Out of curiosity, how large is your environment? How many users?
Take a look here: VMware: Run Microsoft Exchange Server Software on a Virtualization Platform | United States
If you scroll down, there are a ton of great documents there. The Design and Sizing documents in particular should help you understand some of the architectural differences. But keep in mind this isn't a trivial upgrade and so you may need to work with your Exchange team to understand the impacts of upgrading.
Hope this helps!
Matt