Not sure where to look for these

You could try Year One Restorations they may have what you need. I also regularly check local Craig's List ads, and maybe your local auto wrecker. As far as your rear sill I make my own. Buy a thin piece of press-board from Home Depot, pick-up a piece of vinyl from your local auto upholstery shop.($15-$20 end-of-the-roll piece) Use the old sill piece as a template. Use a little spray adhesive and your done. :)