rear end ratio to make happy rpms at freeway speeds

Not gonna happen with any of the ratios you listed assuming a "low profile" tire. Back when I had the 70 440-6 RR, 3.54 with G60 x 15's gave up 3K at 70. Those tires show up as 26.4" dia

According to Joe's link, that combo is only 66.6 mph at 3K, so either my memory is off or the tire chart I found is a little off.

He's right though, you MUST know the tire size you are going to run.

You may be a candidate for an OD 4 speed.