There are no less then 4 kappa perfect 12 drivers, correct?
Perfect 12 VQ
Perfect 12 DVQ
Can be a bit confusing.
I think any of them would work just fine in that enclosure.
The box was designed for the Perfect 12 VQ
Just looking at some differences and found that the 12.1 is very similar. Some differences to note. It has a higher sensitivity rating and a little lower wattage rating. It's frequency response is from 18 to 150. So maybe the really low stuff has a bit better response.
the Perfect 12.1(which I am using for my build as a cheaper alternative) tends to be much cheaper and has a very similar response. I would suspect their are very few differences. I think they all use CMMD. The magnet may have very slight differences, but the response I would expect to be nearly the same. Either way the Perfect 12.1s in that box would probably smoke anything commercial under 1000 dollars. So don't worry you will still probably get an amazing response. Especially with 2 subs. Just make sure you get a Behringer EP2500 and DCX2496. Also make sure you build the cabinets out of 3/4" birch.
I suggest not making a big fuss out of it. Especially if you paid only 120 for it(the price of a 12.1 these days.)
I hope that helps. I'm building the same sub and using the drivers you bought. I don't think it's a big deal. There may be minute differences between the two but both look almost the same.