Pressuring 1400 even a single PC2000 would be more than enough.
The real issue is that opening. It would be next to impossible to predict how much sub you'll need to pressurise the space.
SVS makes very high quality subs, offers one of industry best customer services, warranty and shipping, but these things are not free. All of these are built-in price of their units. More so on higher end models like SB-13.
If like very powerful bass - you may want alternative you could consider an alternative:
This pair of these bad boys:
http://www.hsuresearch.com/products/vtf-3mk5HPDual.html
PC2000 is real nice sub, but not even in same league as HSU's vtf-3mk5