New SSH keypair
After enough helpful blog posts referred to it, i finally did read (parts of) the ssk-keygen manual page myself:
http://man7.org/linux/man-pages/man1/ssh-keygen.1.html
I went looking for the guy who wrote about using non-standard key sizes, and found some other stuff first— had to switch to the other computer to get my history, as it did not come up in search at all.