I love the Commodore 64. These require SID chips and it sounds like getting the new clones may be the most stable option. It would be nice if they assigned a 1V/oct per SID voice, but they don’t, so you need 4 to get the 4 note polyphony. Though, you could build out a 12 note chord. VCO and filter are combined, but big. Barely room for the VCA and EG. Also, threw in the Polychrome Phaser and a joystick to do cool stuff.