What we're talking about here is a "latter day" sailing vessel, in which things were done a good bit differently than in earlier years.
In a ship of this period each yard had two jackstays. One was on the top of the yard; the other was 45 degrees forward of it. The upper jackstay was used as a handhold for the sailors manning the yard, and various pieces of rigging (and various blocks) were tied to it - such as buntline blocks, leechline blocks, and reef tackle blocks.
The head of the sail was lashed to the forward, or lower, jackstay. CapnMac82 is right about the spacing. The gaskets (the lines that "bundled up" the sail when it was furled) might be passed all the way around the yard or secured to the upper jackstay - probably the former. The sail ends up as a bundle (a very skinny one - thinner than the yard) between the two jackstays - i.e., on the forward upper quadrant of the yard. The bundle, unlike in earlier centuries, was about the same thickness throughout its length. In these huge ships the clews (lower corners) of the sail were hauled up the yardarms (the ends of the yards), rather than to the middlle of the yard as in earlier centuries.
If you don't already have one, you owe it to yourself to get hold of a copy of Underhill's Masting and Rigging: The Clipper Ship and Ocean Carrier. The combination of text and Underhill's beautiful drawings will make everything clear.
The big problem with rigging a model of such a ship is that, almost by definition, the scale has to be so small. (Those were enormous ships!) Much of the rigging was made of chain, which is virtually impossible to reproduce on such a small scale. And such gadgets as the Jarvis brace winches (key components of a latter-day sailing ship's rigging and deck furniture) are almost impossible for a plastic kit manufacturer to reproduce in recognizable form on 1/150 scale. And in more than fifty years of ship modeling (and maritime museum visiting) I've never seen a jackstay represented convincingly on such a small scale. (The space between the jackstay itself and the yard is only a few inches in real life.)
That Heller kit is, if I remember it correctly (it's been a long time since I bought one - and I never built it), about as good in most respects as a plastic rendition of such a ship on 1/150 scale as one could reasonably expect. One problem with it that I remember, though, is the the jackstay eyebolts are represented as little oblong blocks on the fronts of the yards. (That's just plain wrong - yet another example, I'm afraid, of Heller's designers simply not understanding how a sailing ship works.) I like the idea of furled sails. One possible approach would be to shave off the little bocks and carefully arrange the furled sails so the absence of the jackstays isn't visible. In any case, some simplification of the rigging is just about unavoidable in a model like this.
Hope all that helps at least a little. Good luck.