360 into 64

Your quickest,easiest and cheapest option right now is use your 273 manifolds... You'll have to get the weighted(notched) b&m 360 flex plate if its automatic, the trans will bolt up....
What gaskets are you using??? Header gaskets??? They are too thick...a shim style gasket or none, they are 2 machined surfaces. Maybe just use copper silicone??? just make sure you close up the air holes under the exhaust port...
Later 318 and magnum manifolds will work on the passenger side, but the driver side is unique to the early abodies....
I used the hooker 5208 headers on my 64 Dart w/360...


Bob