Unless you already have the engine, the newer LSx engines are the same physical size as the SBC yet can be ordered from the factory up to 427ci as a production engine, and up to 455? ci aftermarket. The 427 crate engine is 505HP before a tuneup, 530 after tuning in mild street trim. While it is an OEM production Corvette engine, it is based on the C5R endurance racing engine, so should operate at all altitudes reliability for years at stockish power levels. It should have acceptable life at 750HP due to titanium rods, dry sump, and other racing tricks unseen before in a domestic car engine. But it is a digital engine that you tune and datalog with a notebook computer which scares some folk off.