I would like to use latex paint to on old plaster walls in a 1800's house. Some of the walls had to be patched with new plaster where the old plaster was removed down to the lathe. There appears they have been coated with calcimine before being wallpapered. I searched the internet on which primer to use before latex and now I'm totally confused. Should I use oil, water based, shellac or Zinsser Guardz?