Re: "1) A mint condition Heathkit H27 (dual 8" floppy drive for H11). Wonder
if it's usable on anything else?"
Yes, it is.
The box has two absolutely garden variety standard Memorex 550 8-inch floppy
disk drives in it (SSSD). They have an absolutely standard 50-pin Shugart
SA-801 compatible interface. They are currently connected to a controller
located in the bottom compartment of the drive case, below the drives (I
think it's a single board computer with a Z-80 and a 1771 on it, but my
memory isn't that good). Anyway, disconnect the cables going to the
built-in controller, and connect your own 50-pin ribbon cable, and you can
use the drives, cabinet and power supply with almost any system that takes
"standard" (e.g. Shugart compatible) single sided 8" drives.