Stainless fasteners should always be used with anti-seize compound. Copper based is usually preferred in high heat applications. You have to reduce the torque when putting any bolt into tapped aluminum threads. Your head manufacturer should give you the recommended torque. This is also another good reason to use a locking fastener. Typically when putting a bolt into tapped aluminum holes you cannot achieve the proper bolt stretch to create a proper bolted joint due to the reduced torque. When you add a compressible gasket to the equation, it is even worse. Therefore use a locking fastener in all cases. I would also use anti-seize in aluminum heads regardless of the fastener material. If the carbon steel fasteners start to rust due to the heat, the anti-seize will help.
