I don't really want to damage a new fork or the CK headset which I could put on other bikes. Happy to use another headset if it's the right thing, not as bling obviously, but I've had good experiences with M:Part headsets before.
How much we talking? I filed the crown of a fork down once carefully, really didn’t take much. Just do it. Otherwise there’s a crown reaming tool somewhere at work but. Just file it down very carefully!
File the fork? Are you absolutely sure it's not just a very tight fit? I'd be persevering to use the ck headset in your shoes