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

TBH, with 4B at stake, I wouldnt blindly rely on AES. I'd use it as the 1st step, and then additionally encrypt its output with a custom AES-like algorithm (change tge s-box, change the number of rounds, maybe upgrade it to 512 bits). Even if my homebrew algo is weak, there's still standard AES behind it.