I don't think so. But Navistar was still producing 7.3L's in Brazil well after 2003 when they were discontinued here in the US. No idea if they're still being produced there. But even if you could find one down there, shipping would be a killer.
Ford remans use a metallizing process on the cylinder walls to restore them to standard size, but Ford remans are $$$. The upside of a Ford reman is that the warranty for it would be honored at any Ford dealer.
When I had an issue with my original engine, I bought a used one from a wreck. It's still running 100k miles later. As they say, your mileage may vary.
What happened to your original engine? Could it be fixed?