1972 Demon with 71 340 casting

i have a 72 roadrunner 340 engine sitting on a stand, but never paid much attention to the changeover,, thanks for the heads up.
regarding early blocks in later cars, I helped junk out a 1974 charger R/T 440, and it had the 440 with casting date of jan 1971. Apparently there was a bunch of extra blocks lying around in 74, so they used them up. I still have the differential and original exhaust manifolds from it lying around somewhere.If we had known that being one of 370 or so would matter later, we would not have salvaged it. But, it was in 1984, and a dead title car. so,,,,
I forgot to mention, my friend had this engine and 10 others lying around when he passed.
I inherited his stuff, and I sold that engine to a guy in western nebraska for his 74 GTX. That was in 2018.
Wayne never sold engines!