1966 motors are very common, you should be able to come up with what you want. 1971 cars usually have Jan, 1970 cast blocks or 1969 cast blocks there are some other dates that were put into 1971s also. The 1970 blocks were put into the most of the a cars and the very late cars got the 1969 blocks. There are exceptions but this is a generally what happened in the 1971 Hemi Build.