I didn't see this link posted and I apologize if it has been.
Here are the GM Performance recommendations for breaking in that 350 HO crate engine. Interesting to note that the break-in period ends at just about 500 miles – and his motor already has 1100…
http://static.speedwaymotors.com/pdf/startupbreakinprocedure.pdfI'm actually putting this very same engine into my '53 resto-mod over the winter.
Cheers, John