I'd wait on ordering those just yet, OP. I'm trying to find the thread, but there is an issue with the KingSpec KSD PA25.6 drives, of which those both are, that make them not friendly with the Clamshell's ATA bus. There was a whole thread where people were saying they were unable to get that model to work in their iBooks; I have the .6 version of the 32GB and was actually able to get OS9 installed onto it, but OSX refused to install.
If possible, I'd look for the PA25.1 version of those drives. It's not impossible to get the .6 version to work (at least not with OS9) but it was a real PITA for me and I can't guarantee you'll ever get it working with OSX.
This issue is mentioned in
this thread, I thought there was a bigger thread discussing it as well but I've not found it yet.
Looks like you can find the 64GB version of the .1
on ebay for a little more than the .6 was on Amazon, provided you trust that the seller in China actually sends the same model listed.....