nice to hear your up and running! its up to you but personally I would leave the JBLs in the dash running off the HU, maybe add an inline bass blocker ( couple of quid, halfrauds ) on the + wire. two reasons why.
firstly, the crossover high 'output' will be too high really for the JBLs as they are essentially 'full range' speakers, basically only the tweeter part of the JBL coaxes will be working, silly to waste the proper backcone part, may give a noticable boost to noises like cymbal's or high voices for example.
secondly, you will get the tweeters with the componant set you buy and they are supposed to run off the high crossover output anyway so why not use them?!
nice looking tweeter locations can be done much easier than this but this is one of the best ive seen.
http://www.talkaudio.co.uk/vbb/showthread.php?t=159311even whack the tweeters near by where the grab handles would be at the top of the doors ( on the roof liner though!) you will notice a lot of difference if you use the proper tweeters.