Some sort of output event like "spawnHomingProjectile" with available targets such as Nearest Player or Nearest Vehicle instead of a velocity? (like the player/bot spawnProjectile only provides a speed and not a vector)
Activating Player, Nearest Player, Nearest Vehicle ("anti-tank" turrets, also targets bots/player vehicles) - they shouldn't fire if that player is more than 10-20 studs away, though.
Why did you highlight the Spread Turret part of the script?