If I understand Mr Cortini right you already have anything you need. He said he can just use the Octatrack to create a song. The 0-Coast is your Buchla. The Analog 4 your EMS Synti AKS (o.k. that is an exaggeration).

If you want to expand: your sources are more on the well behaved clean side. Maybe you can add something more raw analog. A vintage VCO mono or a small Eurosystem (this is ModularGrid for a reason).

And you need of course a stompbox style larger than live fx unit, like BigSky, Mercury 7, Space, Bam ...