Highs....Mids...?

[get me on the road]

I am going to be building some custom speaker boxxes to put on my dash. I did some measureing and the speakers can be up to 6" wide and up to 11" long and up to 3 1/2" deep. I have 2 12" subs which will eventually be located in the center console area. So my question is for the front and rear, head unit speakers, should they be highs if I plan to put 1 set of amplified speakers for mids on the sub box (w/2 12'' 's)? I also plan to put 1 set of tweeters in the truck. If the front head unit speakers should be highs or mids, what size should I get i.e. ?"x?" and ohm, watt things like that, and where can I get them?(like it says above they can be up to 6"x11"x3 1/2") The truck is a 89 1500 silverado, regular cab. Thanks in advance for any help