Welcome Malleus, to the Epic world of hurt, where points are a royal pain in the rear.
EDIT: Those Knights look prety cool. You could add 40K/WH bits to them if you want them to look more Paladin, Lancer like, etc.
http://www.bitzbox.co.uk/Double Chain Fists are too worth it, IMO... I've had them used against me in the past, before the Titan Weapons had points values and they can take down some big stuff... Especially with Knights adding to the D6 pot for multiple opponents... They also gain an extra -1 to be hit so Snap Firing at them is at -2 to hit... WOT!.. They work out cheaper than Subjugators (who admittedly have a better minus to be hit and some cool shooty weapons...) but the Subjugators, despite their HUGE claws only get a 3D6+Caf... and a +2 Damage roll.
Deathstrike Cannon Titan Head... yeah, 90 degree fire arc would be better... and bring it into line with things like the Leviathan's Doomsday Cannon.
...I suppose the 75 points, -1 Armour location save and minus half the Titans movement just wasn't enough payment for a 200cm, Indirect Artillery, 2+ to hit, 6cm template with a -2TSM...
Question... if the Deathstrike Canon gets hit and fails it's save... does it make a weapon location roll or a head roll? Is there, in effect no longer a bridge to hit?