Is your gearbox Ford or Chev?
It's only the Chev gearbox casings which suffer from the "Mooney job" Bob describes.
For all the abuse these gearboxes suffer they are very strongly built and when you find a wreck it's usually wrecked because of engine problems rather than gearbox.
The gears shouldn't be hard to find - I'd be doing that rather than using that one given the pain in replacing it later - especially if it is a Ford.
Amazingly the gearbox in the attached image turned out to be mostly OK despite appearances - you can see it in
this gallery.