A street engine and a performance engine take different paths through the machine shop. You don't prep or perform the same machining operations to both because their purposes are completely different. So, by adding an aluminum head to it, the owners intentions with his own build would likely have to follow the same path through the machine shop as the performance or race engine would. But 300 HP is not an incredibly high expectation for the Slant, especially if adding a turbo or nitrous. That increased power level doesn't automatically mean shorter lifespan as long as the engine is prepped according to it's intended use.
Just as a point of reference, there are several guys running my aluminum cylinder head and a similar aluminum head made by Sissell Automotive on their Chevy 6 cylinders that are making in excess of 900 HP with a turbo as big as a basketball and have to drive a 50 mile trek on city streets and interstates as part of their racing requirements for these Outlaw type shootouts they compete in. Many people do what they do simply because they can and for no other reason.
