I did not go through all of the options on the Ebay ad, did they offer some specifically for the CX? The CB750 valves are not an exact fit. I measured some years ago and I seem to remember that they were too long for the CX. Kibbelwhite can make you valves, you just have to decide if you want to spend that much. Unless your valves are bent a bit, a good machine shop should be able to do grind them enough to make them work. The other option might be to look for a used set of heads.