You are pushing it. 1000 words is 10 bits of entropy per randomly chosen word. 70 bits of entropy is probably crackable by a government agency.
Edit: I checked and unless I mixed some zeroes somewhere it looks like the current bitcoin hash rate of 200 million TH/s can crack 92 bits within a year. log (200,000,000,000,000,000,000*3600*24*365) / log 2 = 92.35