Design me a reliable big block that will beat an LS in the quarter. It's already been done.
You built a 68 Barracuda with a 440 and it won't beat the LS? You don't know what you are doing.
Now, design me a big block that will beat an LS in the quarter and get better than 20 mpg...................Oh, and do it for free.
Go away. I won't help you.