1968 340S Coupe 4spd
Your intake should be a 2531915 (this will be in the top behind the carb)
Your heads should be 2531894 (they may or may not have an x by the plug hole) If they do not have the X take off a valve cover and the casting # will be there.
It has the 340 exhaust manifolds.
The carb would be a Carter AVS with 4424s on the front lower left.
The block should be a 2780930 on the drivers side along with 340 cast into it.
My build date is 10-02-67 and my block is vin stamped on the top driver side bell housing flange. This will tell you if it is the original engine.