Six of one half dozen of the other. 340 usually forged, shot peened, forged crank, small journals, floating pin forged rods, and internally balanced. 4.040 inch standard bore with all the good stuff from the factory. 360 is a cast crank, large journal, pressed pin forged rods and externally balanced, 4.000 standard bore. Both had the good heads, not really much difference if built the same. Of course you can do the same with 318's and 273's and they will run very well also. Reliability is a factor of build, stress, usage and maintenance. All Chrysler engines are long haul, overbuilt engines. We have a 273 with 300,000 miles on it and it still starts and runs like new. It was never babied. What do you want in a car?