I have a pair of 2004 10" L7's on a jbl 1200.1. They pound in small custom 1cf. boxes.
One 10" L7 should sound great on 600w I like the 10 L7 better than the 12" L5. The L7 is going to hit a lot harder.
There is the major kicker sub-forum in sound domain. Great place to hang out if you want the info you're looking for. Just go to their forum and DO A SEARCH 12L5 vs 10L7.
Your question has been asked 3,000 times. They really like 1.75cf. ported 10" L7's. They pound. If you can't afford that amount of space, a 1.25cf box is good for a 10" sub.
If space is an issue at all, a 1cf sealed box is nice .75cf sealed box isn't bad sounding as long as it's built sturdy.
Polecat and Ghost are the major kicker competition guru's.
Kicker Subforum