Unfortunately there's no simple, quick answer to that one. The size and number of blocks and deadeyes you'll need really depends on how thorough a job of rigging you do. The rigging of a ship like that, when she's in service, includes hundreds of lines. There are all sorts of perfectly legitimate reasons to omit some of them. Most of the lines that are attached directly to the sails (sheets, tacks, buntlines, leechlines, clewlines, etc.) are relevant only if your model has its sails set. Many modelers (including me) don't build their models in that configuration. If you leave off the sails, you're fully justified in leaving off a pretty big percentage of the running rigging.
The George Campbell plans that you've ordered include specs for the blocks and deadeyes of the real ship (that is, the lengths of the full-size blocks and the diameters of the full-size deadeyes). So all you have to do is divide the numbers on the sail and rigging plans by 96 to get the scale sizes.
I'm a big fan of the britannia metal blocks and deadeyes from Bluejacket (www.bluejacketinc.com). The Bluejacket parts don't come in enough different sizes to cover every single size of block on board the real ship, but you can come close. (You can, for instance, easily get away with representing 11", 12", and 13" blocks with the Bluejacket 1/8" ones.) You probably want to use the "metal-stropped" blocks.
The plans also give the sizes of the rigging lines. Remember: rope sizes are generally expressed in terms of circumference. To get the diameter of the rope (which probably is what you're interested in), divide the figure on the drawing by pi (i.e., 3.1416 - or by 3 if you're not ridiculously picky about such things.) Then divide that figure by 96 to get the diameter of thread that will represent the prototype rope to scale. (Or, to keep life simple, just divide the measurement on the plans by 300.) Again, you probably won't be able to match all the huge variety of lines in the real ship, but six or seven different sizes will make a pretty convincing variety.
The deadeyes present some problems. After you've junked the plastic ones, you'll have to work out a way to secure the replacement lower ones to the hull. (The Cutty Sark's lower deadeyes are a little unusual. They're secured by iron strops to chainplates that are riveted to the insides of the bulwarks. The chainplates pass through the pinrails; the deadeyes sit on top of the pinrails. Revell's deadeyes, of course, are oversized - and the pinrails in way of the deadeyes are too wide. Study the plans, which clearly explain how the real ship is put together. It shouldn't be too difficult to make one of the Bluejacket styles work.
One tip: don't feel like you're under some obligation to buy all the fittings you'll need at the same time. At first, buy enough deadeyes to cover the lower ones on the lower fore, main, and mizzen shrouds and backstays - the deadeyes, that is, that are secured to the bulwarks. (By my casual count, there are 34 on each side of the ship - in two or three sizes. That means you'll need six dozen deadeyes to start.) I'd suggest buying twelve dozen (uppers and lowers combined), so you have enough to set up the standing rigging of the lower masts and the backstays. While you're at it, order a few dozen blocks in various sizes. When you get low on blocks, order some more. Bluejacket's service is good; waiting for a shipment of blocks to arrive won't slow you down significantly. In any case, if you're just now starting on the model, you won't need any blocks or deadeyes for several months.
Hope that helps a little. Good luck.