I've seen some tools that map from Vim GUI themes to console, but what about the other way around? A reader sent in vim cterm2gui2cterm (GitHub: 97-109-107/vim_cterm2gui2cterm), a tool that maps from console themes to GUI themes and back again.
It's a Python script that has a dictionary that maps colours from the console number to a hex equivalent (
xtermMap). It outputs the result in a cterm or vim colour scheme file, so you can easily load it as a colour scheme. It might be useful if you often switch between gVim and console Vim and want to unify the themes.