Don't do this. You're talking about a build that's coming in at around $3k with the Palette, where if the objective is a drum machine and bass synth, you can get new, prebuilt stuff from several different firms for a fraction of this. And if the functionality seems limited, just go out and buy more drum machines/bass synths...don't worry, you won't be getting CLOSE to that $3k unless you either go premium-grade or acquire a truckload of those devices.
Seriously. I'm looking at a Reverb listing right now for a minty-looking ORIGINAL Roland TR-909 that's priced at about the same amount as this build would cost. Nothing above will sound remotely close. Or...there's an Elka Drummer One for $2300. That's the original Kraftwerk machine, the one that was discombobulated by them to make up Wolfgang Flur's drumkit after it was used as-is for their second album and "Ralf und Florian". Again, nothing above blahblah...
And for the second time this afternoon, I find myself writing these words: modular is NOT a panacea. It makes sense in some situations, but trying to 1:1 replace existing devices for their basic functions with modular gear is either a fool's errand or one weird-as-hell flex.