I'd either get an insane headunit like the Pioneer Stage 4 or an Eclipse sound monitor, or a combo headunit+DSP like a top of the line Alpine+PXA-H701 or Sony CDX-C90+XDP-210EQ, or something + Audison bitone, JBL MS8, whatever like that.
I'd follow it up with an older 4 channel amp to run an active front stage with about 100 watts to each channel, a 2 channel amp for the rear fill, and two 10" or 8" subs in a sealed box. Probably just some older Planet Audio subs and amps, then something like Alpine Type X comps in front, or something of similar quality, Type R comps in the rear