I bought two 50-pin IDE to USB adapters and plugged one into an original iPod 3G hard drive w/software still installed, and I plugged the other one into the 128GB KingSpec 50-pin SSD, and I did a Disk Utility restore from the iPod HDD to the KingSpec SSD. They then both showed up as the same device on my desktop, but when I plugged the KingSpec into the iPod, it gave me the bad hard drive (folder) icon. I reset it, and still, no dice.
I've settled on buying a batch of 80GB 50-pin IDE hard drives for my retroMod audiophile iPod 3G's, since the new metal housings I acquired are for the 40GB models, so they should accommodate an 80GB drive just fine. I'm looking forward to actually finishing this batch, so I can see what a revitalized iPod 3G really looks like!