Why all the twin linked plasma? The only things tau should ever use twin-linking is for deathrain (for when you need to hit at any range, and be useful against 90% of the targets you find) or when you're sending in a suicide suit with twinlinked fusion to kill tanks.
Get more firewarriors. you need at least 2 squads of at least (AT LEAST) 10. Obviously, you'd want 12. You can keep the suits alive (against shooting, anyways) by giving you commander stims and/or irid (or both), shield drones, and attaching him to the FW squads, it works like a fucking charm.
Knowing your model limits, I'd run it like this:
Shas’el, 2 S.drones, stim, irid, TL Missile pods. 128
12 FW w/ shas’ui, markerlights (140)x2
3 deathrain (TLMP, TA) suits. 153
3 broadsides as you posted: 240. Consider cutting suit to add shield drones.
Broadsides can take out AV 14, the death rain take out his AV 12-10. If he deploys poorly, you can deprive him of all his armor in the first 2 turns. Then, the rail guns and death rains can focus fire on MEQs and probably waste 3 marines a turn or so, since the twin-linked nature of these guns means they won’t miss. Firewarriors shoot camp in cover, collaborate with lights to deny cover saves.
Now, you’re at 801 points, and you have 200 points to put into either 20 kroot, another 140 fire warrior group, a 175 railhead if you feel you need one, or a pair of suits kitted to whatever suits your fancy. I’d suggest dakkasuits (mp/bc/mt, with the team leader using the ion gun) nowadays, since cover hurt fireknife suits effectiveness. Failing that, go for another pair of death rains, and convert some guardsmen to gue’vesa to reenact “operation human shield.”