I don't think i've missed anything crucial. Still on the fence on Catalyst Audio vs more Verbos stuff. Looking for demos of CA b100 clones, please post if you have them : ) . Especially for the oscillator.

8 oscs
14 VCAs (6 lpgs, 8classic)
8 envelopes (well, more if you count the multiple outs, but 8 controllable by hand)
7 filters
3 FX
Lots of controlled randomness.
The control base will be ipad with Lemur
Mixing is going to be external or maybe on a skiff

Everything is hands-on touchable, absolutely no menus, screens - its ment to be played like a piano :D

A few things...first up, the mixing really needs to be internal. Buchla's mixers also did quite a bit with CV over spatialization and weren't merely level controls. Have a look at https://www.modulargrid.net/u/buchla-system-interface-model-227 , which is the original 200/300 mixer I'm familiar with. Note that you have control not merely over stereo panning, but quadrophonic spatialization, in addition to a bunch of other functions that, to be honest, really bring a level of convenience to a synth mixer that you mostly don't see now. The closest thing to this would probably be Koma's quad performance mixer, which would make a decent stand-in for something like the 227.

Filters...if we're not talking LPGs but actual, typical VCFs, you can probably do with less. Buchla's gear was more about wave combination/shaping, so typical subtractive methods didn't happen much. But note that: 'much'. There were still a few filters that made it into typical Buchla architecture that we'd recognize, and of course there's all of the spectral-type filtering that was a lot more common starting in the 200 series. The Bark filters definitely satisfy that need. Also, there's only one thing I can think of that's like a critically-significant Buchla 'filter', the 296 (see https://www.modulargrid.net/u/buchla-296), and that would be the Frap Fumana. Not cheap, but definitely in a similar vein to the 296 in function and usage methods.

Lastly, the controller. If you're not going to use touchplates, you're not going to get the same...ah, hard to describe...'behavior' out of an iPad. The iPad (or any other tablet) will correct a lot of the weirdnesses that the various touchplate controllers brought to playing the Buchla. For example, one thing I was warned about is that setting certain touchplate voltages before spending some time settling into the studio will likely later result in values that aren't what you had in mind. Yes, these things could be that biologically sensitive! They literally bring you into the instrument circuits themselves, if that makes sense.

Also lastly (yeah, yeah...), it could be smaller. Yes, big 200/300 systems were hulking things, but Don built those modules in a larger format (4U-ish), and you'll notice that present-day 200e setups are pretty small, physically. Even the System 200e we see Marton Subotnick using in "IDOW" is a smallish affair when compared to his original 100 rig. You can do more with less in a typical West Coast setup, to be honest, so it shouldn't be too necessary to go quite so big here.

Mind you, Buchla stuff is getting cheaper if you go outside of Buchla itself. Northern Light, Roman Filippov, et al are gradually getting the Buchla-format pricing under a modicum of control, so one could make do with a few of the nosebleed-pricey Buchla modules augmented by a lot of other not-Buchla that doesn't cost so much.

Thank you very much again! So very informative :). I've remodeled for a smaller starting setup - ModularGrid Rack - the Koma Mixer & Fumana are both superb & superbly expensive piece of gear - and after watching demos - Fumana is the choice. For mix i'll do with Scan & Pan's for now; maybe when i finish the rack i'll go further with this. Should be enough ? Suggestions ?

Much more scrunching:
ModularGrid Rack
This is a little more like it. Notice that this comes in at a hair under $10k, where your original build was $17k+. Two harmonic oscillators, two complex oscillators, both the Fumana and Koma mixer. Ample modulation sources of the right sort, four LPGs with four matched EGs. Clocking and sequencing are a lot more complex, plus the Serge TKB clone was added as a pretty much 1:1 replacement for the similar Buchla touchplate sequential controller. Signal input with envelope follower and, yes, quad outputs. One note, though: the fixed filter bank in the top row could be subbed out for a multimode VCF of the right size; I felt, however, that since West Coast is about waveshaping and since the Instruos have wavefolders onboard already, some sort of fixed equalization-type filter was more in line with the timbral alteration idea.

While it's not exactly Buchla appearance-wise, believe me, this is in the right ballpark without spending an arm and a leg. Cases, btw, are a pair of Erica 126 hp powered cases, optimally housed in one of their dual case end-panel sets. Very ample power supplies in these, so the draw I came up with is nowhere close to their limits.