The 79' four headlight look is not good, swap that for a 78' nose brother!!
I wouldn't run anything but a pair of bad ass 6x9's in that back dash with a legit 2 channel amp to power them. No front speakers at all. Old school style... head unit, (Alpine, Pioneer, or Kenwood EQ), 2 channel amp and bad ass 6x9's. Prolly some rear deck sound deadening. That is it. Then 2.5" dual exhaust with 40 series flowmaster mufflers, like the super 44's, long tube headers and NO crossover pipe so it lopes like a beefy cam!!