Any suggestions for socializing a single kitty

The cat was found outside with his brother when he was around 2 1/2 - 3
weeks old. His brother didn't make it and he's been alone since. He's around
7 weeks old and is doing a lot of biting. He's had a stuffed animal in with
him all along as well as other toys and his crate is kept in an area where
he is around people a lot. I've been so tempted to put him in with a litter
of kittens who are a few weeks older but he hasn't been tested for FIV FeLV
yet.

The other day he launched himself at my face and bit me so this is becoming
a problem and I don't feel right adopting him out until he has more social
skills.

Any suggestions?

W