There's no way to know how much correction to make. Just try printing them & experiment. Your print time will have to be longer than usual. If you are using VC (variable contrast) paper you can try using your softest setting.(posted 8549 days ago)Overdevelopment increases grain size and contrast, so the pictures might not be to your liking. I would suggest with a small enlargen, rather than larger, since smaller enlargements take a shorter exposure than large ones.
The Massive Developer Chart (www.digitaltruth.com) shows normal time at 10.5 minutes for ASA 400, and 12.25 minutes for ASA 800, so you basically overexposed by 1 stop. This shouldn't really be a problem to print, though the contrast might be too high.