Should I use protect_class=22 or 26 for a colonial-era historic reserve?

Here in New Zealand is a particular historical site, known for being the location of a colonial military base and a battle during the Invasion of the Waikato. It is now a historical reserve named 'Cameron Town Historic Reserve'.

Reading the wiki page for protect_class, I'm confused about what value I should be using. The description for 26 indicates that it is to be used for colonial-era historical sites, so would seem to be the appropriate value, but I'm not quite sure.

Should I use protect_class=22 or 26?