I'd say overdrive and 4:11's if you can swing it and if not then my second choice would be the 9 inch Ford for easy gear interchangability. 3:08's for the hiway and 5:13's for wheelies lol.
Seriously, you need to access what your goals are and be realistic.
If you plan on a weekend toy with some track time the gears will have to be optimized for your planned MPH and ET (ie what RPM are you planning on going through the traps at).
If it's a cruiser/bruiser I'd think something in the 3:23 to 3:55 area would be ideal.
If you plan on "Power Touring" I'd go with 2:56 to 3:08.
With the 9" it would be simply a matter of swapping center sections (used to do it on Friday evenings and got it down to 30 minutes in my younger days).
With the overdrive trans, all this is mute. I run 4:11's, it has nearly identical ratios in 1st thru 4th as the wide ratio Munce and on the hiway 5th gear at 2300 RPM is 70 mph+.
I run a 12 bolt Chevy currently and in retrospect I would have gone with a 9" or my first choice would be a Dana 60. The Dana rear makes all others look like toys. The 9" offers the most gear ratio's and parts availabilty and brake options. The Dana offers ULTIMATE strength period. I literally replaced every component in my 12 bolt but the housing, axles, diff, gears and brakes. The only thing it offered to me was more strength than the original 10 bolt and it would bolt into the car.
OP, I'd recommend looking at Strange Co. they offer pretty much every option for rear axles and they have top quality components and great customer service. PM me if you want to buy my 12 bolt and as soon as I recieve the funds I'll be buying an S60 from them!