Also it was quite common to use several different years parts on the same engine. So far all of the numbers you have provided are early 70's and the -a2a is just what version of that casting for that year. It's pretty simple to follow the codes. Pull off the oil pan and look at the crank numbers. This will definately tell you wether this is a 429 or 460.
Can you get the oil pan off to look at the casting number on the crank?
For a 429 it 4U or 4UA. An early 460 is 2Y or 2YA or anything with 2Y.