If you have a spare pair of hands, run a shop vac next to the rivet while you're drilling it. Should suck any debris away, in theory at least.
Ended up coming together nicely. Losing the DVD drive for now. I'm going to have to cut the bay in half to remount it. It's probably been about a couple years since I've used it anyways. I might not bother.

Looks good dude! What kind of fans do you have up front? If I recall, didn't that thing have something like a 360mm fan for intake?
You're going to some lengths to keep that old case going. Is that THREE HDDs in there? I'd offload that to a NAS and tuck it in a closet. I wouldn't be able to deal with that noise from those things.
Thanks, I'm happy with how it turned out.
200mm fan was up front but I had to take it out to set the HDs there. It is three drives but one is an SSD. They don't spin up much. Since I put in a 4TB M2 I could transfer the data and retire them I suppose.
Excellent idea.