Sigh, the words "Heller" and "well-fitting parts" never seem to be i nthe same sentence (or paragraph, fo r that matter).
Now, Heller's rigging instructions are notorius (search here for user=JTilley for some sharp-edged comments). Apparently Heller's person in charge of creating rigging instructions learned everything they know on the topic from studying wooden ships of the sorts found in in Spanish tourist traps.
I am remiss in not saying ealier to not fully assemble Heller masts, but to make them in sub assemblies (e.g. lower mast; top mast; topgallant) as that makes the rigging much easier. This alos aloows you to get brass wire in them, too. Telle est la vie modélisation.
One of the fiddely details that may make you life easier with the shrouds is to lay them a bit closer to prototype. One the ship, as you face the deadeys, the first shroud goes up from the foreward most deadeye, up and around the mast and back down to the next deadeye aft. Where the shroud passes around the mast, it's bound together with a lashing that is very close to the bottom of the top platform.
Then the opposite side shroud is laid over that in a stack. Note that this makes for a neater "pile" of lines all jammed in there between where the top mast "doubles" the lower mast.
Now, don't try for all that detail--that's a 1/96 scale ship.
In a perfect world, it can be easier to make the shroud up off the kit, then form the eye, then pass that over the mast (befoe th top mast is assembled) one after the other, then bring the lines to the deadeyes one by one.
Malheureusement, l'mond n'est pas parfait.
Keep up the good work, you are doing just fine. You will be ables to use these skills to tackle other projects.
PS, in full disclosure, my first ship ket was a Cutty Sark and it had the horrible Revell vinyl-coated thread ratlines. Having no other instruction, I trapped the bottom "thread" in the plastic deadeye assemblies, and since this was before CA glue, I had to find a way to tie all the little ends of the threads around the top of the mast. Threads covered in vinyl resist knotting, even more so with a jillion knots right next to them. That kit got left behind in a move, and was not sore missed. Sigh.