It sounds like iPhoto is only seeing the cached thumbnails. Do you have the contents of your Photos directory?
Yeah that sounds about right.
iPhoto holds quite a few versions of your photos with the same filename. If you imported IMG_001.jpg from your camera in to iPhone, it will make two copies, one in a thumbnail folder location which is like 100x100px or something small, and then the full size which is 3000 x 2000 px or something.
Depending on what kind of state your old HD is in, you might be able to recover the files you need.
I would see if you can get someone to recover the hard drive's contents on to another external hard drive. That way you can look through the files and folders for your documents that you require. If the hard drive has failed or the platter inside the drive is damaged on the area that holds your full-res photos on you won't be able to get them back easily, without taking it to a professional company that charges extortionate prices.
Take it to an Apple Retail store and kindly ask a Mac Genius if they can try to rebuild the volume and recover any data to another drive, if you're lucky they might.