Grainy photo; is a canvas a good idea or bad?

The canvas texture is going to exacerbate the imperfections as will enlarging the image since most canvases are rather large. All of those noise pixels get exponentially larger too. I wouldn't make a canvas with it. You could try making a poster of it first at a rather cheap place like Walmart. It will give you an idea of how it is going to look at a really large size without being as expensive as a canvas. Their biggest poster is 20x30 for $19.  Much cheaper than a canvas.