the only way to know is to cut and try. The problem being is that the CK base plate is milled exactly to the specifications of the bearings that are used in CK headsets. That spec may or may not match onther manufacturers bearing spec. Some things that would have to match up exactly with another manufacturers headset and bearing are, the pitch of the inner race of the bearing and the depth of the pitched section, inner race inside diameter, inside diameter of the lower cup, etc. Variation of spec between the two of as little as .01mm (or even less) could create problems. You can try, but it'll likely be tough to find one that will work for sure. I've tried a few "cross overs" in my time, but never found a base plate or crown race that was 100% cross compatable between manufacturers.
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