Picking a rear gear ratio

[DRJDVM's '69]

Okay so I got my rear wheels and am about to order a rearend..

My tires are 27.75 diameter, and I'm planning on the T56 Magnum with 6th gear of 0.63.

I've done all the RPM calculators online, so I know what the RPM will be with diff set-ups.

My question is.....so what cruising RPM do you shoot for?

In my '69, with 3.73 and TKO 600, the motor starts to kinda lug if I go below 2k in 5th gear....but thats a carb car..

With the Barracuda, it will be a modern 6.1 HEMI, fuel injection etc etc.

I'm think a 4.10....and the 4.30 will be too steep and make 1st gear useless.... the 3.73 seems alittle low

4.10 at 70 MPH =2189
4.30 at 70 MPH= 2296
3.73 at 70 MPH= 1992