Hi and welcome,
Better the link to the rack, so we can check the modules...
ModularGrid Rack
To complement the Turing Machine a quantizer would go well
This is cheap and two-channel
https://www.modulargrid.net/e/doepfer-a-156
You talk about delays and effects, but I don't see any module of this type in your rack. I imagine that you intend to take the signal to the strega, but I would recommend at least some effects module with good modulation sources.
https://www.modulargrid.net/e/make-noise-mimeophon
https://www.modulargrid.net/e/qu-bit-electronix-nautilus
Do you plan to use an external mixer for the different sources?
This has a good quality/price/characteristics ratio
https://www.modulargrid.net/e/tesseract-modular-tex-mix-master-section
https://www.modulargrid.net/e/tesseract-modular-tex-mix-4-stereo-channels
I see you have plenty of voices, but if you want to keep a second oscillator and if the DIY issue is not important, for a 3340-type VCO I would recommend something like
https://www.modulargrid.net/e/make-noise-sto
https://www.modulargrid.net/e/nano-modules-ona
To complement your modulation sources I would add an additional mixer/att, highly recommended
https://www.modulargrid.net/e/intellijel-triplatt
And think of some clock divider, sequential switch, utilities are very important.
And definitely, start with a 9U case, even if you don't fill it at first, you will end up needing space, you have modules that consume a lot of HP.
Do not be overwhelmed, start little by little and you will see what you need.
Greetings,