Tearing it down

If the left side of the block, above the starter ends in "340 - ??" then it's a 340. The right side of the block will have the casting date/year. That's the same for any 360 or 318 too. I'd like to know what you have (definately) before too much more is said. The short, short version IMO: If you have a 71 or earlier 340 or a 360, run the 360 heads and degree the cam "straight up". If you have a later-than-71 340, or 318, run the 318 heads and advance the camshaft 2°.