Jaki Liebezeit is another story - he was a jazz drummer in Cologne in the '60s and worked in Manfred Schoof's quintet (until Sven-Åke Johansson took over) among other groups. He could really cook and was very inventive. And if anyone wants to sell me some mint Can LPs, get in touch...
Guru Guru's rhythm section (Uli Trepte, bass and Mani Neumeier, drums) were part of pianist Irène Schweizer's trio in the mid-60s as well, before Krautrock took over, though at least at the outset Guru Guru were more of a "free rock" band, so the connection seems more logical.
Christian Burchard, while less of a powerhouse than the above players, also worked with Mal Waldron, Charlie Mariano and other modern jazz greats, both in Embryo and in other contexts.