66 Dart GT HT Whatsitgonnabe?

There's an exhaust leak btw the manifold and head at the two middle cylinders on the driver's side. I've tightened the bolts about as hard as I dare and the gasket is brand new. I wonder if I need to have someone check the surfaces for squareness.
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They could be warped a bit - I'd have a machinist plane them true after you pull the engine to refurbish the engine compartment.