The high frequency response (say 2000 up) will be determined by the tweeter you use. You can buy the exact same tweeter used in many high end systems. Low frequency response is where matching an existing speaker system will take some work. You can buy very fine drivers at reasonable cost, but mating them to an enclosure is both an art and science. I suggest that you first play around with cheap and easily modified plywood boxes until you come up with something good. Only then begin to worry about fine furniture grade carpentry. As for crossovers, your best bet is to biamp using an electronic crossover that is easily reconfigured for frequency and slopes. You can do tests in an hour or so which would take a week if you were playing around with passive crossover design.
Finally, a shortcut is to clone an existing design instead of reinventing the wheel.
Finally, a shortcut is to clone an existing design instead of reinventing the wheel.