there's also a sizing issue to consider; some (tubeless) tyres and rims go together better than others do, because the rims are slightly different diameters. I have no idea how the rims you have stack up in that respect though.
cheers
The HED Belgium plus are wide, and from what I have found on the internet, Schwalbe One tubeless 700x23 measures 26.2 at 75psi on Belgium Plus, IRC Prolite Tubeless 700x25 measures 28 at 75psi
(The Conti GP 4000 SII clinchers in 25mm rub against the frame on the back and are close to 30mm wide)
The IRC 25's may fit (assuming that the ifo is correct)
The Specilized Turbo Cotton clinchers (24mm) measure over 27mm wide on my rims, so to be on the safe side, it looks like 23's will be my best bet
so far, I'm leaning towards Schwalbe Pro One in 23mm