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HQ - 98
Shas'el - Twin Linked Plasma Rifle - Missle Pod - HW Multi-Tracker
Troops - 240
Hammerhead - Ion Cannon - SMS - Targetting Array - Decoy Launchers - Multi-tracker - Target Lock
Total - 498
Hi - I'm a fairly new player, but I say ditch the SMS for the burst cannons. You are gonna want to be in sight of the enemy anyway to fire your main gun. With the extra points you can give photon grenades to one of your FW squads. This often buys you an extra turn to maneuver so that the enemy won't sweep into you, and you can shoot him when the fighting ends.
Yeah, on an Ionhead I perfer burst cannons to SMS (though not on a railhead). I'd use the points to give the FW's 'ui's though, not grenedes.