Pictures would definitely help identify it. Even if you can't, you can measure them up and match them with what is available. You may even be able to adapt a near miss with a few firebrick. There are a few online stove parts sites that have pics and dimensions.
Cast can be welded but I recommend a talented individual for this task. The braze will give up quick under the heat.
Don't feel bad, I can't get grates for mine either and I know exactly what it is. The company is still in business but they no longer make the boiler. The grates are available but there is no one left at the factory that remembers which foundry they are at.