If the stock ratio is worse than like...a 3.08, I'd definitely recommend upgrading just for driveability reasons. Those old tall gear ratios were supposedly for "economy" but tended to just result in a sluggish vehicle.
Based on this old forum thread I found, the base rear gear ratio (in a Torino at least) with the 302 and a 3-speed manual is a 3.00, which would be perfectly fine.
http://forum.grantorinosport.org/fou...topic6640.html