Oldtimer: speaker best option

Hello together, I have a vintage car and want to refit it with music. Unfortunately, the possibilities are limited. I have a built-in space for the center front front of the windshield in which originally the only speaker of the original monoradio sat. In addition, I have two built-in places in the back of the hat rack. I don’t really know about Car HiFi but would like to achieve a good result among the given possibilities. I’m the type who has a mp3 “in g The radio is the link below, because there are buttons and front panel in OEM style:http://www.ampire.de/MOTOR-3.htm?… Now to the speakers, I know the sound is preferable to the installation at the front, but I would like to have stereo. There are stereo speakers suitable for the front mounting position, e.g.:http://www.classiccarstereos.com/…/KNW1006.html Is something to consider or prefer two higher quality speakers in the hat rack? Or as a third possibility to equip front and rear? Closed still, would it make sense to support the whole with a small sub and seperate power stage? I completely relegate cables, the car is standing as a bare coach in the garage anyway and I am anyway laying the harnesses.