Unlike almost every other sefment in plastic scale modeling, there is almost no after-market for ships.
Which is largely because ther eis great depth in the scratchbuilding supplies market. So, rather than specific-to-kit, the supplies are specific-to-themselves.
Which becomes complicated.
A Model Shipways cast metal 3/16" (long) single sheave block is really scaled to be about a 12" block in their most used scale, 3/16" = 1'-0" (1/64). But a Model Expo 5mm block from one of the European makers (corel, mamoli, et al) arent actually scaled at all, just vaguely whittled.
The blocks by Syren, and also Bluejacket are far, far better for detail.
The human eye can percieve, to scale, about 6 different sizes of line at typical home modeling scales (like 1/96--1/8"=1'-0"). A ship like Constittution used several dozen sizes of line, measured in circumference, often at no more than 1" size difference. The lines were laid upp either hawser-laid or shroud/cable laid--a distinction requiring a microspoe at 1/96.
You can buy white line and dye it to the finished color. Standing rigging was tarred, and that tarring was a black coffee sort of brown black. The running rigging should have as least a hint of khaki to it, as the best lines wer made up of hemp fibers.
Be advised that sometimes the best "line" is, in fact, black annealed steel wire (available from Bluejacket for one).
The Bluejacket plans will help immensely, for having line sizes and block sizes called out.
There is a convention that warships are not rigged with sails, and merchant vessels are.
Make sur to give some thought to how you are mounting the kit to a base--that kit builds up into a large construction.
The one most important thing to address, in my book, is in beffing up the hull thickness at the gunports and similar areas. The hull should be about 7/64" thick at the gunports; several of the threads here address really good ways to achieve that.