Am I getting ripped off?? Cat. issues

Hi, I'm new here but this seemed like a good place to ask for help. I'm thinking about buying a used Chevy G1500 cargo van. It's a 99' and the seller has disclosed the following

*water pump failed quite suddenly one day, the engine overheated on the way to the grocery store. (it has been replaced)
*It has no current inspection due to the catalytic converter, which has the "service engine" light on. (i.e. the diagnostics in my original add.

My question is this... do you think that there is a possibility that the blown water pump could have damaged the engine, and what do you think is the likelyhood that when I replace the Cat. theat the "check engine" light will turn off.

Any thought would be apreciated.

Thanks!

-Jay :confused:

Without know how hot it got we can not say.

When buying a used car or truck find a good repair shop and have them look it over good.
Money well spent.
MT