Thanks again naf. I think I'm on the right track now.
Small update, I got the HD's resorted.
I drilled four new holes, and mounted M4 captive nuts to the HD caddy:
four more new holes in the bottom of the 5.25 cage + some grommets, and I keep my "double dampened" anti-vibration mechanics:
the drives will go in reversed, so the wiring will be in front of the case. Here's a shot from the rear:
and from the front:
One happy discovery. It's very easy to reclaim the captive nuts from previous efforts. Those aren't cheap, so this is good news. I just screw a nut into them, and tap them with a hammer and they pop right out.
On a completely un-related note, I had a few odds and ends to order from newegg, so I snagged a new fan just because it intrigued me.
Xigmatek. I like it. I like it a lot. I think it and a few friends need to find their way into this build.
I'm off to get the cages drilled and mounted now. More to follow.