I'd advise looking at installing your front speakers in the kick panels as demonstrated in feral4mr2's post. Those dash speakers will probably not be sealed or baffled well at all, and I'd think just to look at the pictures they'd stage and image horribly.. With formed pods in the kick panels you may be able to develop better enclosures and set your staging angles to suit.
If there's no room in the kicks you could look at door pods, which can acheive the same effect. I suggest the kicks first as it'll maximise the forward positioning of the loudspeakers and allow for the best imaging (separation) results.
I'd also not bother with rear fill in a cabin that small, as you'd ideally want the car to stage from the front, yes? You'll have no problem with just a pair of components (5.25" or 6"/6.5") in the front.