Yep, Bakster, you've got the small one. This isn't the first time Revell has botched up the scale of a model. (I sometimes wonder if the people running the company nowadays have any understanding whatever of the great skill those artisans back in the fifties and sixties put into those kits. If the Revell Santa Maria actually were on 1/96 scale, for instance, those exquisite little crewmen would be about four feet tall.)
The good news is that the parts breakdown and the detail on the two kits are identical. The bad news is that, all other things being equal, in the sailing ship arena the smaller the model the more difficult it is.
I don't give orders to fellow modelers, but if I were you I'd get three sizes of line in each of the two colors. (The cost difference between two and three sizes is negligible, and it's no harder to work with three than with two.)
I'm afraid the smallest diameter offered by Syren (.008") will look awkwardly big on a scale that small. If you rig the ratlines with that stuff, for instance, they'll look enormous. You need to find something smaller.
I don't recommend regular sewing thread. It generally has cotton in it, and cotton is notoriously hygroscopic - it stretches and shrinks with changes in the humidity. For the smallest sizes of rigging I personally like either silk thread or wire. Here's a source for very fine silk thread: http://www.jsflyfishing.com/fly-tying-thread .
Bluejacket also sells a very fine (.005") thread that handles nicely. It's cotton, but I suspect it would be a good ratline material: http://www.bluejacketinc.com/fittings/fittings10.htm . I'm talking about the stuff listed as "New rigging thread." I wouldn't use it for long runs of line, but for ratlines it ought to be fine. If you do use cotton thread of any sort, it would be a good idea to run it over a cake of beeswax.
If you haven't rigged ratlines before, I'd suggest the "needle through the shroud" trick. Get the shrouds set up nice and tight. Cut a piece of stiff paper (index cards work great) to fit neatly between the channel and the underside of the top, and draw a series of lines on it to set the spacing of the ratlines. Then thread the smallest needle you can find with a piece of the finest thread you can find. If you're right-handed, you'll find it easier to start on the right side of the gang of shrouds. Shove the needle right through the shroud, then the next one, and so on. When you're done with one mast on ones side, put a tiny drop of white glue on the intersection of each ratline with the foremost and aftermost shroud. Let the glue dry (really dry), and snip off the excess thread with a razor blade or a really sharp X-acto blade.
You don't need to cross this bridge till you come to it - and you're weeks away from that point. If, when the time comes, the thought of all those ratlines is just too intimidating, don't be afraid to admit it. Consider leaving the ratlines off. If the shrouds are set up nicely, and if you've done a good job on the rest of the rigging, scarcely anybody will notice.
Both Revell Mayflowers are beautiful kits - among the best styrene sailing ships ever produced. The potential is there for an outstanding model. But don't get overwhelmed by the complexity of the rigging. If the model ceases to be fun, there's nothing wrong with changing your approach and leaving some things out.
Good luck.