trying to decipher my engine codes

[67chevy_hotrod]

So i have my 67 Chevy with a rebuilt small block. The Casting number is 3970010 so i take it its fair to assume its a 350 correct? I am also aware that there is another code i need to pull that i can find on the passenger side of the engine? is this on the head or on the block or what? please help me out i would love to know the history of this engine also i know that 350's were not put in 67 so is there a chance this could be the original 327? I am dying to know and any wisdom and or knowledge is greatly appreciated!!!