Typically they are low mileage and haven’t been rebuilt. Some had forged cranks. Many had HD rods. People will blow smoke about thin-walled cylinders, less ribbing, more or less nickel in he casting. Blow it all off. The only drawback is that it will be low compression. So they need a performance rebuild. No biggy. They are great rebuilders. Keep the block, crank and heads and toss the rest.