that header fits ANY year of slant six. I know those 6-1 headers are know for bad ground clearnece. i think it will work might hang a lil low. try checking out slantsix.org if u havnt already
i checked what the guys at slantsix.org had to say and ya they will fit the early a with mods:
You have to space the engine up, grind part of the steering box off, bend the idler and pitman arms, and pound all kinds of dents in them. After all that, they hang very low.