gbody parts has a nice headliner package. Or if you want to do it local. Pick up a board at a local autosalvage. Then go to a local headliner shop & have it put in.
Many fabric stores also carry headliner material that matches... I did mine black Costs 10$ to do 1 headliner. Also make sure you use super 77 or 76 for the adhesive... don't skimp out on cheap brands for that... I learned the hardway.
Just make sure the backing is CLEAN! This means all that old dry rotted foam needs to be removed with a wire brush or your fingers.