Everything evolves with time. We now have computers, smart phones, flat screen TV's and even electric cars. The 340 was a great engine in it's day, but it's day is long gone, it's the day of the new Hemi's. The only reason I would even consider using a 340 was if it was some sort of collectible car, but even then, if I wanted to drive it, I would put the 340 in the basement, and drop in a Hemi.
I love my little Hemi Dart, It starts up every time, runs like a scalded dog, and averages about 23Mpg ( I got close to 27 when I drove to Carlisle ), and the exhaust fumes won't melt your retinas...