So I may have located a PowerPC ThinkPad, but it
doesn't have a hard drive. $ 
  I understand the standard one was a 1.2GB SCSI drive,
part number 30H1467. 
I don't know that machine specifically.  But I have a machine using a
SCSI laptop disk; I found that an IDE disk in a SCSI<->IDE adapter did
the trick very nicely.  (The disk plus the adapter was about as
physically big as the original disk - and digitally much larger.)
Depending on your tradeoffs, that might be worth investigating for you.
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