I've just designed a Veroboard layout and cut the tracks-.... I’m next going to use par4ken’s modern variant of the Akai SS-1. Interesting that you should post the EA 1972 design as it’s also fundamentally the same thing. As I mentioned above, my slightly simplified version of par4ken’s circuit will dispense with the front channel mixing facility:
View attachment 56706
I now need to go and check if I've some suitable close tolerance metal film resistors.