And...
It's finally done. Pro tip for all my home viewers. While it
IS possible to use '67-72 seat covers on a '60-66 full foam seat frame, and some of the later colors, patterns and fabrics may look more attractive to you—
DON'T DO IT! Resist the temptation. Getting the back rest cover to fit and look reasonably good is a major pain, and requires a lot of custom fitting and fussing.