Kent- It really is not that difficult of a question to ask yourself. Most SHELBYS dont have their born with engines so would you like to drive something that sounds like your vacuum cleaner when driving it or would you prefer the wail of a highly tuned Big Block echoing off the buildings or canyon walls, I compare it to wanting a Cobra..... A small block 289 is fun- But a 427 SC is breathtaking, I would choose the latter. Here is a picture of mine with a 427 medium riser, 99 percent of people dont know the difference or really care, but what they do like, is going for a ride and screaming like a girl SLOW DOWN/SLOW DOWN!