I looked through my manual and it tells me that my transmission is geared at 3:91. Does this help anything? Certainly not my wallet

but it is a step in the right direction. Does anyone think that a re-rebuild of my carb would be worth the effort? I'd like to try and keep it stock, but if it is not worth the effort, what would be a good carb to use in lieu of my Rochester B?
I ran my truck until I got to a 1/4 tank yesterday and according to my odometer, I put 69 miles on it, using 3/4 tank of fuel. So with a 20 gallon tank, that's 15 gallons used. That leaves me with 4.9 mpg, if I did my math correctly. This seems on the low side. Maybe I should adjust my idle? Could I be dumping fuel into the carb and the fuel not being burned efficiently?