I have a big LR/LRC sync mess. Any suggestions?

I have ~250GB of files in LR at the moment which I have (had) sucessfully synced to LRC running on my home desktop. The problem began when I noticed I was running out of space on the drive where the synced images were located. From Preferences I changed the location for the sync files to another drive with more space and when prompted, confirmed that I wanted to move all files to the new location.

The move had not gotten very far when my machine black-screened and restarted (this happened a second time as well). There was no obvious way to restart the move and but I did have some success by pointed sync location first to the original drive and then to the new location. However, when LRC indicated that it was finished with the move I quickly found some problems.  First about 100GB had not been moved. Second, the file structure was not the same between the drives - on the original it was Lightroom Sync/Mobile Downloads.lrdata/various device subfolders and in the new location all the files are top-level in Lightroom Sync. Third, many of the previews in the From Lightroom collections are unlinked from the files and I am unable to relink at the folder level as I get a null pointer error.

So far I have tried a few things including rebuilding the sync data but nothing seems to happen - LRC seems happy with the state of the sync.  Any suggestions as to how I can resolve? I do not want to have to resync 250GB of data but will do so if needed.  The only reason I haven't done anything yet is that I obviously don't want to blow away any raw data in the cloud and the confirmation dialogs seem to indicate that is what will happen with everything I've tried.