The Apollos might be the "Hybrid" 400 series, they might even be the pizzabox
425.
Whilst not pure Apollos, they have the advantage of smaller size, DOMAIN/OS compatibility,
and
built-in, supported SCSI for disks (just not big ones).
Whatever you do, don't throw out DOMAIN keyboards/mice please. RI isn't on my
route home, otherwise I'd probably bite for something.
The HPPA systems probably have the possiblity of running NeXTSTEP/HPPA, definitely the
BSDish HP-UX variant.
As you said, big, unless they are the tiny 9000/712s