Does the Minibrute 2s have a clock out? Assuming you'll be using that with your rack? You might get recommendations to use smaller modules, like maybe FX Aid XL instead of Beads, maybe Bastl Ciao! instead of the Audio Interface II and ALM headphone output...the idea being to free up some HP to add some additional VCAs or utility modules.
I have the Minibrute 2 (keyboard version) but I honestly haven't yet used it much and so am not sure if it has clock out capability. I have a Hydrasynth Desktop (which I use as a clock source for my Rackbrute 6U). I've read quite abit about trying to build drums into a smaller rack like this and to avoid it if possible (BIA)...do you really need that one since you have the Minibrute 2s? Just throwing things out there to consider...I'm farthest from being any sort of expert like others who will respond, but based on feedback I've gotten in the past, those are things I would look at initially.
Here's my Rackbrute 6U setup fyi if you're interested: 
JB