Whats the deal with 340s?

I grew up in the late 60's early 70's. We called 340 cars giant killers for a reason. There is a nostalgia thing about the 340 to some of us older guys. My 340 isn't anything special, but I have no intention of parting with it. I have a teen and a 360 too. An engine builder friend of mine told me to bring him either one, and he can make it whatever I want. Just tell him how many $$$ I have to spend.