My try using rdarktable. On an impulse i took a different route, and inverted it in gimp and then treated it in rdarktable using negadoctor. Don’t ask me where ths idea came from 
but I’m quite pleased with result. Still a bit too green maybe in the skin? Should the shirt be blue, or? Hard to know what the colors actually where originally.
Nice pratice though, thanks, would have been fun to try it on a full-res scan.
a sligthly different interpretation:
third and final version, I’ll stop now 
for some reason I didn’t notice the dark shadows, so I lifted those a bit…
