I just went through and installed GPGTools for mac mail, and installed the key into facebook with no issues. (Well I copied just the 'random' set of numbers and the fb site told me to include a bit more of the header/footer of the key ). ] It all seems to work (perhaps they fixed the issue?)

... the challenge now is how will my email come through on iOS!? Any recommendations for that? I saw https://ipgmail.com/