66 Barracuda Big Block

The early A's have narrow front frame rail. That means you will have to cut out/modify the fender wells. They also are not suited for the large BB bell housing so transmission tunnel modifications would be required. Once you jump through those hoops, handling will most certainly be an issue unless you plan on driving 1/4 mile at a time. IMO, early A's and BB don't mix very well. 67 on up is a much better choice. 65'