63hz would be great to help move some upper sub range to the front of the car to help the midbass blend but it has been my experience that not many midbass drivers are able to play that low and not distort a ton. From messing around with my 3 way system I found that the less I asked of the midbass the better it sounded, and the lower it was able to play.
IE having the midbass play 63-400hz worked well. If I asked the same woofer to play up to say 800hz it lost some of its ability to play low and became muddy and I had to move up to 80hz to clean it up. Guess kinda FYI /shrug
I have heard several systems with JL components in it. Of the 5 or so 3 sounded great (1 with Coaxials

) and 2 really struggled with the midbass frequncies and sounded hollow. Do some proper deadening in your doors and some frequency management and I am sure they will sound great
Fej