I think the Profile T2 bars are 31.8, not sure.

I would go with a Ritchey WCS headset, it's got the same bearings as a King but without the name. I would say 'quality' too, but since King is made in the US people will argue the King quality is higher. Don't feel like that right now.

Same with stem - I would get a Ritchey WCS stem. An older one will do just fine, you can find them for pretty cheap. They DO make the newer WCS 4-axis in 26 diameter. The stem will be a lot lighter than the Thomson. The Ritchey also doesn't have such a big shift in +/- angles, but if you need a taller stem, the Thomson should work.