In blending, I don't think there really is any such thing as "proper ratios" - it all depends on the character of the wines you are using, and your personal taste. Having said that, though . . .
Pinot Noir isn't often blended with anything else, possibly because French winemaking laws wouldn't permit it (in Burgundy), and possibly because blending with other red grapes wouldn't result in a better wine. In this case, I'd be concerned that the Syrah would overpower the Pinot Noir, and you'd end up with three batches that all more or less tasted like Syrah, with some tasting a little thinner. I haven't done it, but my guess is that you would lose most of the delicate flavors of the Pinot Noir somewhere between 10 and 20% Syrah, or even before that.
Before you bottle anything along these lines, do some "bench tests." Mix up a few ounces each of various ratios that you are interested in trying, and see if any of them strike you as better than the Pinot Noir or the Syrah individually. If so, go for it. If not, resist temptation and just bottle them separately.
Doug