If it is in usable condition, I would hesitate to modify it too much, if at all. If the interior parts are burned out and corroded it probably isn't worth fixing it up to original specs, so your options are increased substantially.
I have some thoughts, but it might be easier if you first went to
http://donkey32.proboards.com and reviewed the batch-fed rocket stove designs. Think about using the stove body as a bell, perhaps even keeping the existing flue and baffles, if they are in good shape.