Crazy gas mileage rambling

[JointTech]

So the main question is realistically what is the farthest distance you can travel on one tank of gas?

End goal being to travel as far as possible in a 4x4 67-72 truck/blazer.
Must use a points distributor and carb. no electronics.

So what engine would we start with? 6 cyl? Diesel? SBC?

How much gas can you realistically carry? At 7 pounds per gallon a custom 350gallon tank is 2450 pounds of fuel. So we start with a 3/4 ton truck just to carry it.
Plus the weight of everything else you will be carrying in the truck. Which then affects gas mileage...

6cyl might be nice for mileage but going up a hill with 3000 pounds of gas and gear might not be optimum and give the opposite effect.

OD auto trans? 4speed? 5 speed manual? 2.7x gears? will it leave the line with weight with those gears?

throw ideas and thoughts at me.

yes zombies are coming and i dont want to be anywhere near LA when they do.