Well I imagine sourkraut is about the same as kimchi, both with regards to Zone blocks and sodium content. Regarding Zone blocks, Saurkraut is 1 block per cup (same as cooked cabbage). I think finding anything that looks pretty similar to a given ethnic food will get you close to the real values. For example pumpkin leaves are likely very close to spinach, collards and kale: 2 cups per block.
Let me know if this helps!