You don't need any kind of swap mounts, thats money wasted, take the mounts off of the 318 and they will bolt right up to the big block, both big block and small block have the same bosses on the block, put the engine right in, get b-body headers and go driving. My brother has a 64 plymouth savoy, had a wide block 318 we installed a 426 hemi, right back in the same location, same k-frame as your car.