2.93:1 ring and pinion, or complete Sure-grip 742 with same gear ratio

AJ/FormS said
65mph with 26" tires is
2700 with 3.23s
2460 with 2.94s
2310 with 2.76s

For best mpgs at these rpms the cruise-timing will likely want to be over 50 degrees.
You can modify your Vcan to get 22 to 24, leaving 26 to 28 to come from the Initial plus centrifical. Which is easy peasy.
So then, IMO, any of these ratios will be fine for cruising.
But you know, a slanty is gonna be working pretty hard to get up to speed around town, in any case, but more so with the 2.76s, lol. And there goes all the gas-money you saved. The 3.23s are the Go-To for a small-engine dual-purpose car.
The FIRST trick to fuel-economy is to get the ignition-timing dialed in. The closer to optimum you get it, the more closed the throttle can be made to cruise on.
The Factory Distributor is gonna need to be modified no matter which rear gear you choose.

That is a lot of what I calculated.
Some of it based off the 3.23 in my Barracuda (built 440/727 that barely gets 10 mpg at 65 mph).
Some of it based off an old M-body I had (318/904, Edelbrock 650 on an RPM manifold, dual exhaust) that had 2.93's and would get 15-16 at 75 mph all day long.
The Fury will be running a mild 400/727 and probably Holly Sniper EFI after break-in. And for my freeway driving 65 is the low end of going with the flow.
Also, I'm kind of "old school" about timing; Run it with the pump gas I would regularly use, advance the timing until pinging under load, then back it off just enough.