You can enable the Hide Uncommon Elements filter in the Select Type dialog to leave out uncommon element types and thus find the ones you need easier. 
Hide Uncommon Elements filter in the Select Type dialogOnce Hide Uncommon Elements is enabled, 
Specified property typeIf the SysML profile is loaded, are listed in the Select Type dialog. |
If the Stereotype tag types are being specified, metaclasses are not filtered out. |

Metaclasses in the Select Type dialog |