Although you will find a lot of chat on the web about various ways to "paint" that top surface, it is important to realize two important details. The original porcelain surface is actually like glass being melted onto the metal frame -- no paint comes near the durability and stability of such a process. Paints that are strong enough to withstand both the heat of the stove and the abuse of hot pots generally are made of quite toxic materials -- and every time you see such a paint discoloring, you can be sure that you are evaporating poisons into your cooking zone. That is why all the paint companies say no. Even the flat black stove pipe paint which could handle the temperature is not appropriate for a food surface.
The best option is to see if you cannot purchase a replacement top from the manufacturer -- often a very cost effective solution. The next best option is to find a service where you can have your top stripped down and re-coated with porcelain -- like the factory original but in the colour you want. Just to prove that that exists you can check out one company in California: AntiqueGasStoves.com.