You can buy a GM crate motor for $1275 with a 3 year/50,000 mile warranty
The warrantee is applicable to models that originally came with 350's. For any other applications such as this, it's one year/12K miles. I've installed crate engines in my '70 Chevelle, '73 Monte Carlo and will be installing one in my '58 Impala

.
But IMO that's a better deal than a remanufactured or bone yard engines. Why you ask? Because if anything internal goes wrong within the warrantee period, you just bring it in ANY GM dealer and it's covered...parts and labor

. So if you live in Ca, take a trip to NY then develop an internal engine problem you're covered.