Just putting it out there...Calais V S2's 19's - the same as SSV S2's
I also have issues with my drive way so haven't considered lowering my slo-mega wagon so know where you're coming from.
19's might look nicer than stock on your Caprice but not make the gap look too big
The reason I suggested the Cal V's over SSV's is that they don't have the black shadow and the centre caps are silver not black - you might be able to put Caprice centre caps in (just a thought...)