My vet got back to me, and said to go ahead and use the wormers that I always have for kittens. He was really nice about understanding that I didn't want to come in (he's not in our town.) and pay a vet visit on top of everything.
Henry has to be at least 2 months old before he can be fully wormed for all worms, and 2 pounds. He is neither 8 weeks old, nor 2 lbs.
So, I'll probably have to worm Krypto as well, since he licks the cage, the kitten, etc.
In fact, I'm going to adjust all of the cats that come in the house's worming schedule to coincide with Henry's, just in case.
Gwen, thank you for the information on Interceptor. I'm glad that someone's used it for so long without issues.
Thank you, Rottenrot, for your addition to the information.
Love All Life, Thank You For Posting! :)