It's not going to be so simple, unless you find an already existing design for this combination.
First, you'll need a cabinet.
JBL L100 Century
It describes a closed 65 liter cabinet for that woofer. It will have less boomy bass than the smaller 44 liter ported cabinet used in the L-100.
And if you haven't seen these, read them too:
http://www.jblpro.com/pub/obsolete/2470.pdf
http://www.jblpro.com/pub/obsolete/radial_horns1.pdf
JBL says the compression tweeter can go as low as 500 Hz, and the horn is made to be crossed over no lower than 800 Hz.
Once you build a cabinet, measurements will show what diffraction peaks or valleys on the tweeter's low end must be taken into account as you design a crossover. Measurements of these drivers – while mounted in the cabinet – will also give you real world impedance measurements as they vary with frequency. Speakers never have a single impedance value. Designing a good crossover requires knowing impedance vs. frequency for the range of the driver.
I recommend using a low-pass filter for the woofer too. It will beam noticeably as sound gets higher than 800 Hz. Why have that when it can be avoided? With a proper crossover, the difference in impedance between the woofer and tweeter can be easily taken into account.
I don't know much about using horn loaded tweeters in a DIY build, but you might get useful suggestions if you ask questions here:
Lansing Heritage Forums