Very psych intro - nice!
Have you tried spitfish? It's from a suite of VSTs that are free & bloody fabulous.
If the de esser in that set isn't much chop for you you'll really have EQ those syllables - get him further away from the mic, use a screen etc etc.
Blockfish has a great preset for close up mic replication that'd compensate for moving him back.
Good song, even terrific but you do have to deal with the sssss. maybe get him to make it a spitting feature of his vocal style and emphasise them.