I was chuckling because you "clearly" stated your "priorities" in your post #15...
and repeatedly asked for "best mpg possible"...
then you compared the performance of this "truck motor" designed for low end TQ to a "vette" motor designed for high rpms performance (apples to oranges)
a car only uses around 40-60hp to maintain hwy speed depending on the car wt...so motor rpms @ hwy speed does pretty much determine mpg....go any deeper than about 3.08 gears and mpg will be less and that's not nearly enough to to give it some balls
best solution for best performance and best mpg on the "truck" motor is a OD tranny to keep it at 2k=60mph with much deeper gears to give it some gonads when it downshifts WOT