The '53 GMC Hydra-Matic was the first GM pickup with an automatic. Chevy didn't get the auto until '54. They are somewhat rare but not impossible to find.
Your toe board is very rusty and that is a Hydra-Matic only piece so you may have to find a donor cab to repair that. The other rust I see in the pictures can be fixed with readily available patch panels.
Of course there is no telling what the pictures don't show.
If the truck has sentimental value, you said your wife inherited it, I'd say its worth fixing. But don't go into a full restoration expecting to make money or even to recover what you spend.
