Didn't mean to throw you for a loop. Koa would work, and for a multi-scale, you are using longer scales for the low strings to balance out string tension. Look at putting in carbon bars on either side of the truss for stability, and you have a truss rod for counteracting string tension and adjustment. You mentioned a bright and crisp with good articulation, and to me that just says a denser/stiffer wood like cocobolo or pau ferro. Layering in 3-5 sections will add a lot to stiffness, but this isn't exactly the same as density for a bell tone like you mention. For stiffness, picture hard maple as a good baseline - It's arguably the ideal neck wood. Koa would be on a less dense/stiff side of that, wenge, coco, bubinga would be on the denser/stiffer side.
I referred to it as bell-like because that was the image I had in my head for the voice of the 8-string multi I was working on. To me thats more than crisp and articulate, but rich in harmonics and with singing sustain. There are a lot of factors that make up a tone like that.
-density of the neck wood
-bridge, nut, and fretboard material
-pickups and placement
-type and gauge of strings, etc.
My last guitar had a 25" scale rosewood neck, carbon bars, a maple cap over a resonant swamp ash body, and hot humbuckers that used Alnico 8s. I can tell you that is incredibly HIFI sounding. It's voice actually stunned me at first because it was so different from a straight up maple neck/mahogany, humbucker guitar. People talk a lot about tone woods, what material for this and that. The final answer is that they all change things - BUT TO WHAT DEGREE - and, they all work together as a system, Hope some of this is useful and not just me blowing hot air!