318 >>>360 in a 75 dart

318 AND 360 are not balanced the same. you can use the 318 converter with the correct 360 balanced flexplate or get a properly balanced converter for the 360/904. The ports size on the 318 manifolds is too small for the 360. The drivers side exhaust manifold from the C body will come very close to if not touch the steering shaft unless the engine mounts are jacked around a bit. I'd check with Treblig for a drivers side manifold.