IMHO, amps and sub woofers do not belong in vehicles. A person can go deaf if they wish, but I don't want to join them.
In an older vehicle I'd build a console to house the head unit. I have an affinity for Alpine's and I have one in my Vette and in my Dakota. The 6 disc changer is behind my seat in the Vette and in the center console in the Dakota. Both of the units are 50 watt and produce a quite adequate volume level.