Buy the 2nd Gen truck , good idea....if you get a good one.

360's tow well, but gas mileage sucks....440 will do about 3-5 miles better per gallon.
intake Edelbrock Performer RPM
Cam HUG SEH1016BL-12 ,
Carb.. Thermoquaud make sure it works
.
Before I laid my 78 D300 rclb 440 4 speed dually to rest in 2012,
around town it would do about 12mpg on a good day, 14 on a great day.
on the highway about 12 no matter what day , throw 7500lbs trailer it would do 10-12 depending on the hills and speed.

Truth has no agenda, but those with an agenda make their own truth.
Some of us are so open minded they only see their View