I spent quite a while over-thinking this circuit, then I went back to basics and just talked it through. I couldn't find a similar online, so thought I'd drop this recording out there in case it was helpful for someone else. Do you have a better way, I'd love to hear about it!
Check this game out and grab a copy - you won't regret it!
https://store.steampowered.com/app/1444480/Turing_Complete/
