This article from AllPar for example, only recognizes two 340 camshaft grinds. Do the service manuals show more for the 340? I knew there were a few more for the 360, but not the 340.
This article has a few things that I cannot confirm or deny without finding my manuals. But he is saying that the 72 340 had a smaller camshaft than the others. And then he says that the 73 340 brought back the 68 automatic camshaft