Refer to https://technet.microsoft.com/en-in/library/cc764232.aspx - which details the Physical to Virtual Migration process, tools, checklists and such.
When you say 2 physical servers are you implying a BizTalk - SQL split OR a cluster? A BizTalk - SQL split should be relatively easy to move into a VM while a cluster would necessitate remapping the SAN/Shared Storage.
Secondly, while you may be able to take the NAME's across, you might not be able to take the IP's across because of underlying Network (VLAN) or subnet changes between the VM infra and the physical infra.
if the names remain, BizTalk reconfiguration would not be required.
Regards.