I have an article from an old Car Life magazine showing a 64 Galaxie with a cammer installed. If I recall correctly it is one of the early SOHCs, with the spark plugs towards the bottom of the chamber, not the top. Pictures showing the engine from underneath show that it is not a sideoiler, just a standard 427. Maybe that's what your block is, one of the real early sideoilers designed for the early heads. Pretty cool find, in any case...