Have you tried taking two predators? One Annihilator, one Destructor, autocannon paired with LC side sponsons, TL LC paired with HB sponsons. For a bit over 250, they divide the risk, and give you all the firepower you need.
why would you ever run a predator with TL LC and HB? There's a place for the AC/LC one since it's cheaper than LC/LC and does the job of popping light/med armour at range. But paying the silly price for the TLLC and then mixing it with HB makes no sense at all. If you want to have one and one do one with AC/HB and one with AC/LC.
to the OP:
a Land Raider isn't a point efficient way to add firepower. What the LR does is bring your nasty combat troops safely to CC and allow them to assault from inside. That's where all those points you pay go. The shooting is _almost_ incidental. If you want more firepower you have plenty of options which are much more points efficient.