Duncan:
You are correct, HEC-RAS does fail on this HEC-2 file. However, I was able to successfully import into RiverCAD and run the model. RiverCAD is a bit more robust at importing HEC-2 files.
I was able to run both HEC-2 and HEC-RAS on your data set. If you want, I can get you the working HEC-2 file that will import into HEC-RAS or the HEC-RAS data.
Sincerely,
Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com