I don't think I would trust a stock Ford Traction Lock. Look into a Truetrac if this will be mostly street driven. A stock '70 case would probably hold up on the street, but if you can find a nodular case with a Daytona pinion housing it would be better. I would use new 31 spline axles.
One thing that I haven't mentioned before, there are large and small axle bearings. The Mustang and Fairlane used the small bearings and trucks and full size cars used the large bearings. I would recommend the large bearings. The sealed ball bearings are fine for street and drag racing, but the tapered roller bearings should be used for auto cross or road racing.