You're welcome. Bear in mind that Essosi Valyrians have access to a powerful custom republican government type called Triarchy, just like Volantis. It'll make them very powerful if you create them as merchant republics because it gives them a number of unique bonuses and mechanics. In order to do that you'll need to make sure the primary holding of Astapor and Meereen are cities, as they'll be castles in the Feast for Crows bookmark. New Ghis' primary holding is always a castle, so you might want to change that too. For maximum overpoweredness you could give an Essosi Valyrian the Empire of Ghiscar, which would make them absurdly powerful in their area, and permentantly eradicate slavery there if you gave them an anti-slavery religion like Moonsingers or Faith of the Seven. If on the other hand you make them feudal, you can have them as Lord Paramounts like in Westeros.