Best bet is to ask others with the same chassis as you, and even ride in their cars for a bit if possible, then modify from there. As you're running Jag front and rear I would think many more people on here would have chimed in with that they're running on their Jag setups. As far as brand goes any reputable brand should probably be ok (such as Eibach or QA1).
Personally I'm getting Hyperco springs, they are used and recommended by Penske. Hyperco make all the springs for F1 so I'm told, and many top teams in other motorsport.
Welcome to Hyperco | High Performance Coil Springs & Suspension Components You can get them from NT Tyres in Adelaide.
Also you haven't mentioned what shocks you have?