That's not quite going to get the best out of those drivers, the box size seems a bit too big and the tuning too low (X10 gives roughly 72l net tuned to about 69Hz as far as I can tell), which results in a big dip in the response below a couple of hundred Hz, with a slight peak near the tuning frequency.

However, depending on how low you want them to get, you might be able to get them to match up ok to the HD15's with a bit of EQ.

Of course, if you were crossing them over at say 200Hz, then the X10 would still be bigger than strictly needed.

A smaller box tuned higher would help fill in that dip which may work better for those drivers if you ever wanted them to be more versatile (eg crossing straight into subs at 100Hz or so).

Yellow is is the unprocessed response in an X10 type box, with power set to keep excursion within Xmax (at least till frequency drops below the peak around Fb).

Green is the same box size & tuning, with the closest match I can get to a 180Hz LR24 response using one HPF and one parametric EQ. That filtering allows it to be run up to the full 1000W program rating while keeping excursion at or below 2.5mm at any frequency.

Blue is an example of a smaller box with a flatter response - 25l tuned to 100Hz for the pair of drivers. This can also take 1000W without exceeding Xmax at any frequency above 85Hz, giving the increased crossover flexibility.

Hope this helps,

David.