Except a stock 340 with 14" tires and 3.55s will not get 22mpg. It's going to take small gears (like 2.94 or less) plus an overdrive transmission to get 22mpg from a 340.
3.23 gears..and i think mine gets 20 plus mpg driven sensibly, but my cam is stock lift with a little less duration...and that would be an Imperial gallon here in Ontario.
