Cam cover gasket use only OEM/Genuine part, either from Mazda or MX5 Parts.
Head gasket depends upon whether your car is standard and whether its 1.6 or 1.8?
We recommend Genuine headgaskets for all 1.6 cars, standard or not.
For 1.8 cars, if its standard then the non genuine Autolink or '5Parts gaskets are fine. If its non standard / turbo'd then we would use a Genuine part. FYI, the 1.8 Genuine OEM headgaskets are really good and are good for over 400bhp.
Give your local Mazda dealer a ring for all genuine parts, they are usually a tad cheaper than '5 Parts / Autolink, but they won't have parts on the shelf so will take a few days to get them to you.