IMHO you can't fit drums into an ambient rack of this size because you need effects plus better modulation tools to do ambient well. I took a crack at what I'd build, see below:
For effects, I added a delay (Chronoblob2), a granular processor (Monsoon), and a dedicated reverb (Erbe-verbe). I switched up some of the mixers, including adding a Mixup which is stereo and a DTM which does nice warm distortion if desired, added a Maths (which I always do), attached a Nin to the Zadar so you can use the Zadar as a playable tool (including long changes over time), threw in a Sloth for weird modulation, swapped an STO for a Dixie II+ (no reason to duplicate modules this early in your journey and Dixie also functions as an LFO), and dropped a Kinks in for good measure.
Weaknesses: I'm not an expert on a lot of the MI modules here so I may be missing something, it's light on attenuators (with only those in Maths and your VCAs), and I would personally probably want a second filter (I'd probably pick a Doepfer ladder over a Wasp though).
Anyway, hopefully this provides some useful ideas!
my tunes: https://stevehand.bandcamp.com/