The overall tire height is within a fraction of an inch of stock, so I didn't change the final drive ratio. The slightly shorter sidewalls do give a somewhat stiffer ride, but not enough to damage anything (or jar any of my fillings loose).
My ‘69 Torino GT came with Cragars on it, I traded into a turnkey hot-rod. Summer of ‘78, great job, hot gal, hot car. Ah, memories...