Looks awesome, I love those multiple carb set ups!
Now I need to warn you all about a problem you might have. The 8 carb intake that I have on my Hemi was originally on a boat. It has the 3 bolt carb mounting pads, and because the engine is placed in a V drive boat backwards, the carbs were backwards. This caused major bog when I launched at the dragstrip because the fuel would slosh away from the main jets. The solution for me was to remove the carbs, re-drill the mounting pattern, and reinstall the carbs facing the right way.
You might have the same problem, but only on one side of the motor. If that was mine I would figure out how to turn those 3 carbs around and make the linkage work. You might want to switch the throttle arm's on the carburetors so that they point up instead of down. Then when they clear the valve cover?
I run the 4 center carbs as primaries, and the outer 4 as secondary's. I have no idea if the outer cylinders are leaner or not while I am going down the highway at cruise. But it does pull down 15 miles per gallon on the highway and is still capable of going 137 in the quarter mile.
I was advised not to use power valves, that they just mess up the tune when you have this many carbs. So I'm not running power valves at all.
Not sure if you have a linkage set up yet or not. But I use 5/16 x .030 wall stainless tubing with 10 – 32 stainless threaded rod inserted through it, and a spherical rod end threaded on each end. And then jam nuts on the threaded rod to secure each end of the tube tight, and to lock the position of the spherical rod ends in place once it is adjusted. It works out pretty good, I think. I have had some problems with the arm on the cross shaft slipping, where it has to pull 4 carbs open. So I'm working on an improved arm with more surface to grip on the cross shaft.
I love what you're doing, good luck with it.