when will you get a return on your money buy removing the 360 and installing a rebuilt 273 to gain maybe 5 mpg? i would remove the 4bbl on the 360 and install a 2bbl set up first and see what happens you can probably find someone that will give it to you for free, next thing i would look at is your timing to make sure your running full vacuum advance in the area of 50 deg total at light cruse, make sure you have a clutch fan, my 4.7 03 dakota only gets about 19 mpg highway with the 5 speed auto turning 1,800 rpm at about 60mph. are you sure the barracuda got that milage was the gear stock? tires stock, speedo working right? Not tring to be negative, but i would try to maximize what i have before i undertake all the work and $$$$