You have two problems here that need to be solved separately.
1. Get the images off the damaged drive and onto a drive that Lightroom can read. Sounds like the tech already did this for you.
At this point you need to decide if you want to use the images where they now are, or do you want to move them some place else.
If you choose to move them elsewhere, use the OS tools (Explorer or Finder) to move them to where you want them. (Lightroom is not a file browser and tends to have troubles moving large numbers of files.)
2. After you have the images where you want them, you need to tell Lightroom where they now are. In the Library module, you will see that your images are marked as missing; and in the Folders panel the folders will probably be marked as missing, too. If your Folders panel does not display the tree like Explorer or Finder does, right-click on a folder and "show parent" as many times as needed.
Then first find/relocate all the missing folders, then find any images that might be still missing.
Since you have already copied the data from the faulty drive to another one, the only is left that you update the new location for the images in Lightroom Catalog file.
Open Lightroom and in the Library Module start updating the folder locations.
And for relocating the missing images refer: How to find missing photos in Photoshop Lightroom
Thank you ManiacJoe! I do know how to relocate missing photos and folders. It's just that I have not had to do 75,000 of them and didn't want to risk messing up my catalog.
I'll give this a try tomorrow.
As with doing anything big, make a backup of the catalog first.