Hello Rick80 !
T7 supports Solaris 11 only not Solaris 10. SFHA support for Solaris started with 6.0.
On a T7 you must have solaris11.3 in primary LDOM. But for Guest-LDOM you have limited support for solaris 10. So you should be able to use a Guest-LDOM as VCS node.
For Solaris 10 in T7 LDOMs : https://support.oracle.com/knowledge/Sun%20Microsystems/2271384_1.html