I was a kid in the 70s but the story I heard about 340s was they didn't last long, a 340 for instance in a 70 swinger 340 may have been blown up and done by 1975 or 1977 and replaced by a junkyard 318. people did junkyard engine swaps instead of rebuilds especially guys just driving these cheap used cars to work. also keep oin mind the 70s gas crunch peopel would also just throw a 318 2 barrel in also and swap the rear to 2 76s for economy.
One of my cousins had an AAR Cuda, and he went through close to half a dozen 340s before he sold it. Damn fast car that was! He lived a couple of blocks from a Chrysler dealer in those days, I'm sure they welcomed him and gladly took his money.
