If you are primarily just cruizin' and depending on how tall your tires are, I would suggest 3.08. That was a very popular gear ratio in Chevys and your 283 should be able to push that '50 along just fine with that gear. It should keep your RPM down to a reasonable level. If you want more zip and are willing to spin the motor more, then try the 3.55s that Matt suggested.

If you want to keep your Ford all ford bolt pattern (4.5 bolt circle) an 8" Ford rear end is also a good choice.

Pat