HiVi suggests a crossover freq of greater than 1800hz. Usually, rule of thumb is to have the crossover frequency one half to one full octave above/below the "cut off" frequency point. So around 3khz-4khz would be better...not too good for that woofer combination.
Those woofers look VERY much like the 7" woofers offered by Styrke. I wonder if they are related at all...
Anyway, unless you are dead set on designing the whole speaker for yourself and are ready for a lot of trial and error, $200 for the drivers and NO crossover parts and not even a crossover design you'd be a lot better off getting a kit from any of the number of reputable DIY dealers. But kudos to you if you want to go it all alone, and good luck.
I've seen it posted that you really can't trust the HiVi FR graphs. Almost all the speakers I've seen that use that tweeter have used it in a 3-way. Sorry I can't remember examples, but it has been a few years since I've looked at HiVi drivers.
As Dan says, you'll want to cross at least one octave higher than Fs, which means 3.2KHz at a minimum. Some of the Morel tweeters can cross low, though.
The North Creek and Acoustic Elegance (formerly Stryke) drivers are not the same. The SA-071 is unshielded, and has a bigger magnet, a stamped frame, and a woven-glass-fiber dustcap as well as the cone. The woven glass fiber dustcap helps control resonance issues that some drivers have with their dustcaps.
I knew they weren't the same driver as one is 7.5" and the other is 7". Back when I bought my Stryke MTM kits John was supposed to be getting shielding cups soon. That was a year ago...I guess I was just hoping I could get shielded drivers soon...
That's ok, I decided my solution will just be to get a projector instead.
At one time I was going to build my own speakers too...I'll see if I can't recall some of the driver combinations I was going to use and let you see what you think. I'm no expert so I have zero crossover designs done for any of them...but it could get you off to a good start.
Reading your starting post, you clearly have no idea of the amount of work needed to get a good sounding pair of 2-ways out of those drivers.
I´m sure the drivers are as good or better than the pricetag would suggest and supposedly better than any drivers fitted in a sub400$ pair, but it still ís not worth it. To much knowlegde/effort needed.