Need gear ratio help!

[04Xrider]

Hey all, I have been away for quit a while, sold my C-10 and now have a new project and I know there is a lot of knowledgeable folks here that know more about this then I do.
I bought a 1948 Chry new yorker and put a 292ci GM along with a th400 trans and getting ready to put a 9'' ford rear end in it.
I will be driving the car approx 70% hwy.
The original car weighed in at 4,170 curb. But I am sure I have trimmed 500 lbs off of that with the 292 and th400 plus other unneeded stuff taken off the car.
48 specs= weight 4,170 Now approx 3,750
Gear=3.54
Torque 215 @ 2750 RPM
HP= 135
RPM @ 65 MPH 2,863

292 CI specs
HP= 175
Torque= 275 @ 2,400 RPM
RPM with current gearing 2,863 @ 65 MPH
with 3.00 gear= 2,427 @ 65 MPH
with 3.25 Gear= 2,629 @ " "
with 3.50 Gear= 2,831 @ " "
I am wanting to get the best fuel economy possible without it being a total dog and I know if I go with to tall of a gear, fuel economy can suffer. But I am thinking with the loss of weight and the higher torque and HP that a 3.00 gear is very doable, but would love to here what some of the more knowledgeable folks here think.

[04Xrider]

Maybe a better way of asking this should have been, is their anyone running a 292 ci with a th400 trans and a 3.00 gear and if so, are you happy with it, and what kind of MPG are you getting?