There was a comment from a guy that said that his Infinity speakers would fit withou hitting witha top depth of 3+ inches. We'll work with 3" in mind. If the speakers you get ultimately do get in the way by a small amount, you can make your own spacers for dirt cheap using HDPE cutting boards from WalMart or Target if you have a Rotozip or jigsaw to cut the ovals out. Easy peasy and solid as a rock.
Something to keep in mind, finding a set of speakers that reach into the sub 80-60hz range won't be necessary, as that is where your subwoofer will be doing all of the work.
I made a nice speaker box for my brother's ram using 4 Fosgate P1's 10's. Loud as hell and cheap to boot. You don't need expensive, high wattage subs when you have four doing the job. It got very uncomfortable for me to listen to long before the speakers got taxed.
I'll do some digging around for those by-nines.