You're quite correct in your implication that, in order to do that kit justice, you need some information that goes considerably beyond the kit instructions. Those instructions are, in fact, a mess - especially the "English translation." That document, which apparently was written by somebody who neither understood French nor had attempted to build the model, is just about useless. The parts of it that deal with the rigging are especially weak - better than those of the notorious Soleil Royal kit, but sadly lacking as a guide to the rigging of the ship.
There are quite a few books out there about the Victory. Actually I wouldn't put the old "Classic Ships" series book high on the list; it's quite a small work, and really amounts to a step-by-step guide to building the old, much smaller, Airfix kit. Not a bad little book, but not of much help to builders of the Heller kit.
Three books stand out. You'll get some disagreement about how to rank them in terms of usefulness for this particular project, but I'll do it this way:
1. C. Nepean Longridge, The Anatomy of Nelson's Ships. The title notwithstanding, this is in fact a blow-by-blow account of how Dr. Longridge built his exquisite, 1/48-scale scratchbuilt model of the Victory, which is now exhibited at the Science Museum in London. Much of the text about the construction of the model obviously won't be relevant to builders of a plastic kit. But the book contains an excellent set of plans (drawn by George Campbell - one of the best in the business), and the chapters on the rigging are worth their weight in gold. In addition to the diagrams, Longridge gives a verbal description of how each line leads. If you can only get one book, this is the one I recommend.
2. John McKay, Anatomy of the Ship: The 100-Gun Ship Victory. This is part of a series published by the Conway Maritime Press. Most of it consists of Mr. McKay's superb drawings, which show just about every conceivable part of the ship in extreme detail. His coverage of the rigging, on the other hand, isn't as clear as Longridge's; it consists essentially of several overal diagrams and keys. It also suffers from some factual errors (none of them really important from the standpoint of Heller kit builders). But the drawings can only be described as magnificent.
3. Alan McGowan and John McKay, H.M.S. Victory: Her Construction, Career and Restoration. This is a superb piece of work, detailing the ship's history - including her restoration as a museum ship (but not quite all of the work that was done to her during the most recent restoration project, just before the Trafalgar bicentennial). It includes a huge set of drawings by the same Mr. McKay - not quite as many as the Anatomy volume, but more than enough for plastic kit purposes. The rigging diagrams in this one are, in some respects, a little easier to follow than the ones in the Anatomy volume.
There are lots of other books and articles about this famous ship, but I still recommend Longridge as the place to start.
Now the bad news: all three of those books are out of print at the moment. Used copies can be found on the web, but they aren't cheap. In a few minutes' search the cheapest I could find were $40 for Longridge, $75 for the Anatomy volume, and $160 for the McGowan/McKay book. I suspect a bit more searching would yield some slightly better prices, but I'm afraid these books are never going to be cheap. If you've got easy access to a good public or academic library, maybe it can help - perhaps through the Interlibrary Loan service.
One other excellent - and FREE - source: the ship's website, http://www.hms-victory.com/index.php?option=com_frontpage&Itemid=1 , There's a great deal of useful material to be found there - including a section devised especially for modelers. (On the bar running across the homepage near the top, click on "H.M.S. Victory," then on "Reference," then on "Model Making 1" and "Model Making 2." There you'll find, among other things, the experts' latest conclusions about her 1805 color scheme.)
Hope that helps a little. Good luck.