Jarred I think you'll have more than enough draft with that block at the top.
It also looks like you can play with the bricks on the sides if you need more.
You're going to want to keep as much heat as you can up and under those pans to be efficient.
There's only one way to find out...and the best part is you can change on "the fly" if need be.
John Allin
14x18 Hemlock Timber Frame Sugar House 2009
Leader 2x6 w/Patriot Raised Flue Pan 2009
Leader Steam Hood 2014 - Clear Filter Press 2015
Leader Revolution Pan and SS Pre-Heater 2016
CDL Hobby 250 RO & Air Tech L25 Hi Vac Pump 2019
06' Gator HPX to collect wood & sap
14' Ski-Doo Tundra for winter work in the woods
Great Family 3 grown kids+spouses and 7 grand kids who like the woods
7th Gen Born in Canada - Raised in Chardon Ohio - Maple Capital of the World..<grin>.