If the plaster is over brick, yes you can use tapcon screws, MAKE SURE the screws are long enough to get into the brick at least 1 1/2". Use a minimum of 4 #8 screws w/finish washers per cabinet(4 in a 16" upper) towards each corner. Also screw cabinets to each other thru the side of the face frames or euro box. When you are all done you should be able to do chin-ups off the cabinet. I have had cabinet boxes fall apart before the back comes off the wall.