Yeah, I noticed that, but then had spent enough time goofing off that I didn't want to figure out what z was in the relativistic calculator. But now you've shamed me into it. Turns out:

z = (f_emitted / f_observed) - 1

So if we're still wanting to get from 530.6THz (emitted) to 399.73THz (observed), we want to get a z of about 0.33. (This is very close to the value in c of the speed I got in my last calculation. Hm.)

And the calculator shows us about 82.7e+6 m/s (0.276c).