Welcome to the forum! A '67 was my first - very nice car. I recently started restoring a' 68, so I'm not far ahead of you. My suggestion would be to start with all of the bushings in the front /rear suspension and also the greaseable joints in the front suspension/steering. These parts are likely old, worn out, and need replacing. There is nothing too exciting about it, but these parts are crucial to ride quality and keeping an alignment.
1968 Impala SS