Genset Synchronization to State Grid

do you have equipment / facilities you need to protect downstream from the proposed location of the surge arrestor? (probably yes)

is there a 3-phase surge arrestor on the primary of that transformer?

Does picking up the phone and asking the transformer manufacturer for recommendations not seem like a good idea then? Would asking a bunch of complete strangers and waiting for a mixed selection of replies, some from idiots perhaps, come across as a much better idea somehow? Isn't there an Electrical Engineer on site who could answer the question instead?