Is there a particular type of Anti-Seize compound that is preferred for use on spark plugs? What temperature rating is needed?
Most people use Copper because it's the most common and cheapest, but beware the cheap/generic stuff that's only good to 600°F or so. I use the Nickel type, not so much for the temperature (2400°F), though that is a bonus, but because there are some metals that you can't use the copper on (Titanium might be one, I'm not 100% but Nickel is fine for it).
As far as temperature rating needed, according to NGK, it will depend on the hot/cold value of the specific plug, but optimal range is 500°C (932°F) and 800°C (1472°F) for the part that extends into the cylinder. The threads are on the water cooled block, so I'd expect them to hover in the 300°F - 600°F range. You can probably get away with Copper, but I'd use Nickel.