I would probably just do a hot wash with my normal detergent. That's what I've done for all of DS2s second hand clothes that I've bought on ebay. Mixed in with a good dose of sunlight on the line, I think it kills any nasties.

FWIW every now and then (particularly because he's toilet trained but has the occasional accident) I do a hot wash just to give them a thorough clean.

By the way, lucky you for getting a good stash!!