Heiland bodies are extremely common (for now). They were mass produced and many companies completely unrelated to Heiland use them (such as MPP, which was the real brand used for the Vader ANH and ESB). There are generic bodies that you can get at lots of places on the internet in the event you mess one up. It's the accessories that are more important. Keep them safe in a box, and you can do your conversion on the main body.