250 vs 292 and 700r4

[Awann99]

Let me run an idea by the experts.
I thought 3.08 gears were nice until I started driving another truck with 4.11s. So I'm redoing the drivetrain on my 69 1500 2wd, I want the get up and go of those gears but it will need overdrive. I'm wanting to instal an inline 6 because it's what the truck originally had. I'm a sucker for inline 6s they are borderline unkillable.
I have a 700r4 to rebuild. I'll have 3.73 gears in the back so the engine will be moving around 2100 rpm at 70.
The only question is should I go 250 or 292? Fuel economy is the goal. (Don't say ls swap) the 292 would have more torque but I hear it's kinda hoggish on fuel. The truck will just be a cruiser. Maybe carry 500 pound of camping gear a few times a year. Anyone out there have the 700r4 on an inline 6?