i did some searching but did not find a clear answer so..

i am looking to replace my 10'' factory subs & tweeters in my doors with a pair of infinity reference 6.5'' separates and want to know will it be a direct replacement if i get a "z enclosure" spacer from ebay? will the depth of the speaker get in the way of the window or prohibit the door panel from fitting back on? how about the tweeter, is it a direct replacement? i understand i will have to use the x-over that comes with the speakers, so no big deal there.
thanks-