Here's what I was thinking.
8 Seekers w/ Combi-Plasma in a Land Raider Proteus w/ Explorator Augury Web.
combine that with a tooled up Lightning w/ Kraken Penetrator Missiles.
I think its a fantastic one-two punch to Spartans.
Use the Scout to park the Proteus close to the enemy Spartan. Use the Exlorators array to get that +1 to your reserve rolls, helping get the jet on the field.
When it does come on, nuke the Spartan, and then toast whatever was inside of it with 16 proffered enemy shots of Combi-Plasma hitting at BS5.
It's expensive, but It would go a long way to help knocking out an enemy Death Star in a Spartan.