Just to correct you a little...
Powder coating is actually an electrostatic process. The object being powder coated is static charged. A very fine cloud of polyester powder is introduced and will adhere to the desired object. It is then baked in a huge oven until the polyester fuses together, then to the object. It is not a very good choice for high heat situations. In the case of engines it is a nitride or ceramic coating process, where metalic compounds are used, not polyester. Most ovens are enameled since high heat resistance is required.
As far as a replacement is concerned, I believe there is one offered for sale in our own classifieds section. It should fit your existing hole!