Mike,

I ran a 4150 750 HP on my old 340 back when the dart went 12.50's. I probably put 10,000 street miles on it without issue. It would get 14mpg if I kept my foot out of it.

-Dustin
67 Dart, 9 second, 392" G3 Hemi
68 Barracuda 340 F/SA