318 to 340 swap.
one suggestion, if you cant swing the cost for headers as they are getting expensive make sure you keep the exhaust manifolds that are on the current motor,,if they are correct and fit,,,they are 1964 thru 66 only,,,1967 and newer will be different,,, so dont buy and headers maked A body,,,make sure they are for the early A 1964 thur 66,,several styles to choose from these days but pricy,,,some will require cutting inner fender wells,,,some more some less,,,ask around on here before you spend money on the wrong parts,,,also do you have power steering??? most headers made for these cars do not fit with power steerring,,,
