Some 340 Questions

Just use teh heads you have, odds are they are 2.02 heads anyway (unless it is a cast crank external balance 340).

The easiest way to tell if they are "X" or "J" heads is to look around where the spark plug holes machined in the heads. If they have an X cast into them they are X heads, if it is a J (or an O with a portion machined away by the spark plug hole) they are J heads. If it has an O they are "O" heads.

Either way they should work fine for what you want , maybe even with 1.88 intake valves. Unless you are racing or really worried about how it pulls above 3500 RPM, the low performance heads with 1.88" intake valves will work fine and sound just as nasty when idling around the drive in.

I have a 340 in a 3360 pound car that runs low mid 12's . it has 2.02 valve "O" heads on a .030 over 340 engine. Might have a very little porting, but not much past a bowl blend and gasket match.

Bob