3.55's and find a set of OD gears for your current manual or a swap to one that has an OD. 3.55's are a reasonble ratio, but still a bit of a screamer at highway speeds without the OD.

I had a 2.94 which was actually quite nice for the highway, still a bit tall but not bad, but on a stock motor it was a bit sluggshg betting up and going. 70MPH was about 2700-2900 RPM and ideal kick down RPM range for the motor as it'd upshift at 80. From that I switched to a 3.55 and the RPMS get into the 3500+ range which was quite annoying and no downshift from that speed. I added a GV OD which is roughly 0.78 ratio. Makes the 3.55 feel like a 2.76. Now that is the best of all worlds. 2600-2700 highway RPMS, really strong kickdown range (2nd gear with the OD on) with lots of room to mile it up before it shifts. But the Gear Vendors overdrive is a very pricy change if you're on a tight budget.

If you have a low gear set in first(no idea on mopar ratios) you can probably do quite nicely on 3.23's or even somethign isn the high 2.X range. If the tires go up easily just on motor torque, you dont need more gear advantage. 440 is a torque monster and as a non sligh wearing street car it will do nicely with taller gears that most will recommend from the performance crowd.

Greg