I am converting an old barn into a place to live. I want to get the look of "old plaster" walls. The walls are covered in older plywood, I have patched all the seams and holes with poly fill. My question is what to use for a primer and can I use stucco for this project? I have seen a product from Behr that will do this job, but I am on a very tight buget and would prefer to use the cheapest products I can to get the effect I want. Thanks.