340ci vs 360ci engine

Stock 340`s are excellent performers and gas milage is ok for what they are. My experience with durability has been -- 73 road runner at 73,000 miles blew a head gasket. At that time add a quart of oil at 800 miles.This car had been down the 1/4 close to 500 times by then; and most of the miles put on it at well over 100 mph. 70 AAR cuda 340-6 an even stronger performer. At 163,000 miles I had loaned it out and it came back with a broken rod and scratched cylinder. I have had a few 360 trucks that were not stock and performed good but were gas hogs. Also none had durability problems and were raced and driven hard too. I don`t recommend driving that way; but I don`t know how else to answer your questions. God bless you, Wayne