I did much the same with my A500/A530 for my cd-writer & hard disks in an old 486 desktop. The a500 and a530 are both powered off the same seperate 250 Watt power supply. I left the A500 and A530 in their consoles, but removed the Hardrive from the A530 to keep the CPU cooler. The addition of a real 68030 and 68882 FPU with a Quantum Fireball in there was pretty warm for the tiny little fan in there.
At one time I had 3 hardrives along with the CD-WRITER in the old desktop, but that was a silly waste of power, as I don't need 6 GB of HD space on a classic Amiga. All my installed software barely fills a 2.1 GB disk, so I removed a hard disk for preservation. There is tons of room in there! Likewise, I require a rather large desk.
What I realy need is a way to pass thru the gvpscsi controller for a Zorro LAN card!