I am unsure how relevant my answer is, given that you had no contact with an Intel-based Mac as I did. However, I encountered [link|http://www.ifixit.com/blog/2009/04/repair-story-320-gb-drive-troubles/|tons of trouble] when I cloned a PowerBook G4 hard drive on an Intel-based MacBook Pro.
From the article above: ''"By default the Intel-based MacBook Pro set the drive partition to its native Intel-only “GUID Partition Scheme,” which prevents a PowerPC-based laptop to boot using the drive. So I set the 320 GB drive to the PowerPC-native “Apple Partition Scheme,” and of course Mac OS X installed with no problems."''
So do make sure that your new drive's partition is set to Apple Partition Scheme, otherwise your PowerBook won't like the drive...