I should have mentioned that 1974 was the first year that the A body cars came with 3 point seat belts! The lap belt cars would NOT have had any bolts there! I did install 3 point belts in a 73 Dart Sport that originally was a lap belt car. The anchor points were already there. maybe it was a mid or late year build. Regardless, if you have no seat belt bolt holes and do NOT intend to install them, the dome light base is adequate to hold the headliner in place, especially if you have the help from an additional person.
One final note....On one of my installs, I had to trim the headliner where it slips UNDER the windshield gasket. I tried to pry it under but it kept buckling until I shaved 1/4 inch all across the front. I mention this because I just read that yours is a "covered" unit. All mine were simply painted.