Ontario is coastal now? Anyways, I don't have much experience with storing cars, but it's mostly the same as storing boats. I'd change your engine oil, put fuel stabilizer in the gas (and run the car for a bit to ensure that it mixes/is in the lines), maybe a bit of oil in the cylinders, disconnect the battery and put the car up on blocks (or just add a bit of extra air to the tires) to prevent flat spotting. Then, just sit back and wait till spring. Just throw the battery on a trickle charger every so often to prevent sulfation of the plates.
By the way, make sure that you've got a coolant and washer fluid mix that's good to about -30 °C (or lower depending on where you'll be in Ontario) so that things don't freeze up on you, unless you're considering heated storage. However, I don't think there's any advantage to heated storage for an E30 (if I can drive my E30 without problem in those temperatures, storing it should be even better - the cold doesn't hurt, it's the thermal cycling of the interior and mechanicals that's the problem).