1000 lbs seems high and possibly overkill if accurate. Slingshot uses "massive" 800 lb center lines and they are pretty darn thick.
FWIW, I bought some Chinese "coated kite flying lines/ 100% high tenacity braided spectra lines 300 lbs" and it is pretty good, but I only use it for 32m steering lines on a race setup.
Watch the elongation once you start using them. I'd give them each a good 200-300lb load before putting into service. That is, don't trust that they did a good job of pre-stretching.
I've bought non-prestretched spectra line before, and on first load a 24m line grew by at about 30 cm as the weave tightens down on itself. Can be dangerous as center lines stretch the most, effectively taking away depower range as they elongate.