This engine came out of a car i bought years ago ran good real good, pulled all the running gear and parted the rest. Just tore down the engine and was going to do a cheap rebuild. Clean it hone it rods mains and rings gaskets and seals. I have no idea what valve springs were used but it does have a crane cam in it. So could have been a kit .? Like I said this thing ran fine for years. And the valve guides have not been machined for different seals. I don't know if the 340 had a double spring and if so would the same seal work on my 318 head?