The link for the 30.2/27.0 headset shows it being 'out of stock'. It seems as though most modern headsets have settled at the 30.2/26.4 standard. If you ask for a new 1" threaded headset that is probably what you're going to get. I'm not saying 27.0 isn't available but it is much less common than 26.4. If your new headset doesn't come in 27.0 just mill the crown seat down to 26.4. It's a common operation and your LBS should be able to do it or find someone who will.