First up, it's a pretty bad idea, when starting in modular, to copy the rig of an experienced user. I would STRONGLY advise against doing this! You would probably find that you didn't understand how the system was meant to be used, resulting in wasting money and effort. BUILD YOUR OWN RIG. And don't try and make some miniskiff, either...putting something like that together and making it function nicely is a very tall order, and requires considerable experience with modular synthesizers to arrive at a useful result. In short, farkas is dead-on when he's saying that it'll be difficult to build something versatile in (actually) 75 hp...because that's what you REALLY have, as the P/S takes up 5 hp right off and your A-119 occupies 8.
Next up: there are not a bunch of different Morphogenes. There's THE Morphogene, and then its sibling the Phonogene, both from MakeNoise, and both initially derived from analog tape devices created by Pierre Schaefer. There ARE other sampling modules similar to the Morphgene...but there really is only ONE of those specific things.
You seem poised to make a bunch of huge mistakes here, most notably by jamming big modules into a tiny cab. Again, if you don't leave space for the various "boring" modules, you'll be left with an expensive and rather unsatisfying noisemaker...NOT a synthesizer. I would suggest two things...
1) Get a copy of VCV Rack. Use it. A lot. This will give you some experience regarding what modules do...and not individually, but in groups and subsystems, which is how you REALLY unleash the power in a modular. Plus, it's free, which is always a good thing.
2) Spend a lot more time doing builds, rejecting them, honing down the ones that work until you arrive at THE SYSTEM. Remember: this is NOT a video game, there is NO score, and there is NO time limit. Plus, absolutely NO ONE gets their initial build right...hell, most of the time, users still don't quite have it on build #10! Polishing your skills at building modular systems is one useful thing you get out of rerererererereREREworking these...and as that skillset improves, you get closer to that perfect build that says "pull out the Magic Plastic". And GO BIGGER...like I've noted, you really DON'T want to do this in a 1-row cab that only has 75 hp remaining. farkas says you can, with considerable effort, and this is true...but from my 40-ish years in electronic music, I can tell you right off that you do not want to do this.
As for what to do with the Rackbrute 3U you've got already...I'd suggest using it with a MiniBrute 2s, then using the Rackbrute to expand that device's functionality. That would then give you a proper sequencer, plus you can use the space (after removing the A-119, which would be useless here) to build up a subsystem to screw with timing, add perhaps a trigger sequencer, put in some logic, etc. That sort of thing...which would be a GOOD use of that Rackbrute. The other build, though...nah. Go with something that's got some ROOM...a Mantis, one of Erica's 126 hp-ers, etc etc. In the long run, it WILL wind up costing more...but then, you'll wind up with something to keep, instead of sticking it on eBay (which is what happens with a lot of users who think they can cook up something usable in a small cab, then they realize they'd basically conned themselves into a waste of time, effort, and ca$h).