You don't want to use an amd29k (even if you could get one). They look cute on paper but their freeze-mode interrupt handling is a Chinese puzzle and unless you use Ken's compiler (previously called 9c), you're stuck with register windows, which tend to need to be spilled when an interrupt occurs, thus slowing interrupt response unpredictably.
The one I used, the 29200, was even worse: it had no main memory caches. So a 16MHz processor could only achieve about 3 MIPS.
