There really aren't any 10" JBL Professional Series drivers that are tuned for use in an eight π. So there isn't a JBL driver option for this design.For use in the midhorn without the requirement for bass, there's a BIG difference between JBLs and the pressed frame Eminence drivers. The JBL is much cleaner. Eminence's Magnums are close, but they don't make a 10" driver. The neodymium Deltalite 10 is a good premium part with reduced HF breakup. But because of that, it rolls off about 1kHz in the midhorn, so crossover must be made sooner than with other drivers.
For an eight π, you really need electro-mechanical parameters like those of the Alpha 10.