Plaster-only tradesmen are difficult to get a hold of, particularly for small projects. It's a dying art and in big demand in Toronto for home repairs.
I've heard good things about Buckner Plastering from a guy I used to know in the heritage building maintenance field. I had Kris's Painting in to patch and smooth plaster walls and I was happy with them - really decent guys who communciated each step of the project and handled additional requests well - but it wasn't ceiling work like you're looking to have done. You can try homestars for reviews of either one, there are a couple of others on there too.
