The new PS3 RTR 4-6-0 set will run on 0-27. Be advised that the earlier PS2 release the year before (with tether) will not run over 0-27 switches due to a low hanging gearbox that has since been corrected.
My Imperial K4 4-6-2 will run on 0-27 but is more comfortable on a wider radius.
As Paul mentioned, any of the "Bantam" steamers will run on 0-27