Header exhaust leak - help!

I have an exhaust leak coming from the center ports of my heads on the header side. Was wondering if anyone on here has any feedback on what gaskets they like, bolt length etc..

My motor is a 318 with the swirl port heads. I'm running Dougs headers and ARP 5/16 - .075 length. I recently tried Mr Gasket Ultra seals but still a leak. Recently heard about Remflex gaskets but seems like mixed reviews.