I found the SICP available for Emacs in the MELPA. It's a conversion of the HTML version made available for free by MIT, into Texi and then generated into Info.
The source for the MELPA is available on github: https://github.com/webframp/sicp-info
There was one open Issue: webframp/sicp-info#2 so I forked the master repo and created a PR from the correction to that, plus regenerating the whole Info as this appears not to have been done in 4 years.
Hopefully my PR will get accepted. If not, then I can still use my own fork, I'll just have to learn how to install a local package with Spacemacs, which I think isn't too hard.
it was accepted the same day.