I just finished replacing the headliner in my '68 122. Not sure if I did it correctly but I didn't use the holes you mentioned except the front pair. My old headliner was not the original, but fit well, so I just copied it. making each section the same size as the old one. I used 2 small lengths of stiff wire to anchor the rear bow to the flange above the rear glass, (had to drill 2 small holes). The rear bow attaches with those 2 clips on either end. The next 3 bows were attached with clips I made by using metal plumbers strap (Use the heavier grade if possible) and a short sheet-metal screw. By starting at the back, the 2 wires give you something to pull against as you work forward, installing the remaining bows. Just get it all hung before you start tucking the edges under. Next, I glued the rear edge under the lip above the back glass, using 3M yellow trim adhesive. Then, starting at the rear, I tucked the edges under on each side, using a stiff putty-knife with a large radius ground on the corners to prevent damaging the vinyl. Lastly, I used another wire to attach the front bow to the dome-light bracket, just to keep some tension on it. I am pleased with the way it turned out, but it is very time consuming.Hope this helps.