The Monogram kit is, as you probably know, a reboxing of an original from the Japanese company Imai. Imai sailing (and sail/steam) kits were among the best ever produced. I haven't built that one in particular, but my recollection is that Imai's rigging instructions were indeed simplified - but not distorted beyond recognition, like so many of Heller's.
If you Google "USS Susquehanna" and click on "Images," you'll get quite a few old engravings and a few contemporary photos. These suggest that her rigging wasn't much different from sailing ships of the period. (That's not surprising. She was built at the very beginning of the steam warship era, and probably used her sails as her primary means of propulsion.) That site also has quite a few model photos.
Be warned: a lot of those pictures aren't of the Susquehanna. I've never been able to figure out how images get on those Google pages, but some of them are pretty bizarre.
Somewhere there may be an original sail plan of this ship, but I'm inclined to doubt it. I suspect those old lithos and photos are about the best you're going to find.
They give a good idea of the leads of the major lines (backstays, stays, braces, lifts, etc.), but they aren't of much help with belaying points. For them, you best bet is to get hold of a belaying point plan for a clipper ship of the period.
Hope that helps a little. Good luck.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.