Hi Brian,
I'm new to astronomy and quite fascinated by all the lists and catalogue systems. I found the following list shows the full list of Herschel's numbering side by side with the NGC numbers.
http://obs.nineplanets.org/herschel/h2500.txt
More lists and sub-lists of Herschel are presented at the following SEDS site:
http://seds.org/messier/xtra/similar/herschel.html
Hope that help, and clear sky!
youn chin