I tried using the TTS+VC setup from the old guide and it didn't work with my version of MorphVOX, after much fiddling I found that MorphVOX needs to be set on Legacy Driver. For future reference I'll just leave here the old guide:
https://pastebin.com/G6kQV2GF

The Legacy Driver thing is in the MorphVOX's Device Settings of v4.4.7 which is what I was using (different from the version used in the guide)