How much you want to spend?
I would look on EBay. If you're going low cost, take a look at the American Classic 27.0. I've used the AC for years and find them reliable and easy to adjust. If properly lubricated, they don't creak either.
Pricier options would be Campag, Shimano, etc.
Top choice would be a Shimano 7400A which you see on a lot of David Hickey's bikes. The Shimano 7400A & B as well as the 600 are really well made with a single bolt for the seat clamp but also incorporating a small set screw which adjusts the saddle tilt. Plus, they're really nicely finished. The 7400A NOS is pretty expensive but the 600 NOS can be found and at reasonable prices. Not sure about the seatposts but the matching stems from that era were made by Nitto.
Bob Ross said:
Can anyone recommend me a 27.0 seatpost with setback?
(Looks like maybe Thompson used to make one, but no longer?)