Now just to decide whom to put where...
As far as I can see, Muscle, Plated and Quick slivers grant stacking abilities. I'm assuming the clot sliver's fast healing doesn't stack, so they may work as the six "shell units," though the numbers make that seem... unnecessary.
3 slivers with stacking abilities means 871 of each of the three types. Meaning up to 2613 bonus hp from toughness feats, and up to 871 bonus hit points from an improved Con score. Meaning about 3000 to 3500 bonus hit points per sliver.
Don't count on Reflex or Fortitude-based effects to bring these guys down. Will saves are more likely to fail.
To defeat this armada, it is important to break up the formation. The heart of the formation is the winged sliver. Taking it down will force the slivers to break down the formation, into a number of landbound formations of up to 452 slivers (about six groups, so they'll form around the "shell units"), potentially after a deep fall. Of course, all that propably will only delay the inevitable...