the rears are a tough call, 4x6" and only about 1.5" depth to work with.
Some Infinity Kappa series or Polks fit. Crutchfields website has good reference to what fits
For the front doors, I think they're 5 1/4, 6.5" will require either cutting or rear mounting the speaker behind the door panel.
I ran polks up front and rear, powerd off a 4x50watt Sony deck, then twin 8" JL audio subs in the rear seat foot well powered by a 240 watt amp. Nice ballanced system.
These guys sell a pre-fabbed board and give great advice on their 911 stereo systems. Dig around on their site for a while.
http://www.caraudioinnovations.com/sub.htm
good luck