Do 305 and 307 small block Chevy engine heads fit a 1964 283 cu in block?

No, the 305 and 307 small block Chevy engine heads will not fit a 1964 283 cu in block. The 305 and 307 small block Chevy heads were introduced in 1967, while the 1964 283 cu in block has different head bolt patterns and port configurations incompatible with the 305 and 307 heads.