American Classic offers a large range of sizes of their classic (!) seatpost, from 25.0 on up...they can be a little pricey. The Kalloy standard post (that has a LaPrade style tilter/clamp) also comes in a large range and is much cheaper, not the same quality as the AC but does the job.
http://www.biketoolsetc.com/index.cg...d=KY-SP243254S
Biketools etc. has the Kalloy but it's currently out of stock, easy to find elsewhere though.