Horsepower with mileage options

A nice cam, good dual exhaust, 4:10 gears and a 2004R overdrive trans. He'll have plenty of pep and cruise at 65MPH taching 2000RPM (depending on the size of his rear tires).
In thinking of a 4 and automatic, how well would the old 518 od trans work for It? Direct bolt in, but does it require anything more than linkages and maybe some driveline work?

Treblig