1973 360
After I blew up my 65 Barracuda's original Commando 273 in November of 1972 (at app. 150K), I put in a 340 from a wrecked 72 Charger. Low compression motor (8.5 to one), 240 net hp. Previous owner had a 3310 Holley on the original Thermoquad intake manifold. That mis-matched setup fell on its face above 4000 rpm. I swapped that intake for an Edelbrock aluminum intake. Now, otherwise totally stock; this low compression 340 was light years ahead of my Commando 273 performance wise. I'm talking about two full seconds quicker in the quarter.
The 74 360 used the same heads as the later 340s. 1.88 intakes, 1.60 exhaust. They breathed well for their day. They might not have been quite as stout as the early high-compression 340s, but they weren't turds, either.