It really depends on what you want. If you want to get the exact same performance, longevity, etc, then a new L31 crate motor would be the ticket. They'll run around $2000 from Summit or Jegs. If you're looking for more power, then another option with the same longevity (and warranty) of the factory replacement engine would be a HT383E crate engine, which is a GM factory produced stroker that is designed to work with the factory fuel injection system (provided you get a tune). Not a bad option at 5,000. If you decide to go LS or carb swap the options, and prices, are endless. Suffice to say you could have a low mileage 6.0L with some aftermarket goodies making more power than the HT383E for less money. Downside is a lot more work involved, and no warranty. And then, of course, you can rebuild your current motor in whatever configuration you want for however much you wish to spend. Sure, you can do a stock rebuild for less than $2000, but IMO you'll be hard pressed to do it with the quality, and get the warranty, found in the GM crate engines.