Exhaust leak at pipe to manifold connection

When we made the down pipes from the manifolds to the rest of the system, we used these to connect to the manifolds. We seem to be having a leak on the passenger side that may be coming from this connection. Need to check for the exact spot but I'm pretty sure this is the culprit. They are connecting to factory 273 manifolds on a 65 Valiant. I looked at the "doughnut" style gaskets but they seem to want straight walls on the manifold side instead of the curved ones on the 273's. At this point I'm thinking we should have used the flat style but this is what we have no and no time in the short term to redo it. What's a good way to seal it up until then?

417Ham-IGdL._AC_.jpg