@MacMiga
It's a fair enough idea. In fact several people have done similar some time ago. I know that, for example, Unitech Electronics offered a product called the Power Tower (or maybe it was the Tower of Power? Not quite sure).
At the time the 486 was a current machine, so it was a new case, with a cable coming out of it to plug into the power connector on the back of an A1200 (or any other 'wedge' Amiga, I guess) and it was wired up for SCSI. This was before all the various clock port expansions became available, so that's not an aspect it addressed.
A possible issue comes to mind with regard to cable length limitations where IDE devices are concerned. But apart from that, sure, an old PC could quite well provide some free/extremely cheap space for a couple of devices and electrical power.