dimensions of the vent and the landing

[gomezcarsonk]

Good evening,

employee monitoring

I am in the final stages of building my first Pompeii pizza oven using the Forno Bravo plans. My oven has a 970mm internal diameter with a 600 x 500 opening to the oven.
I am ready to build the entry arch and the flared vent. I would like to have some help with the dimensions of the vent and the landing please.
Regards