I got a SNAFU in my project...

I need to mount a 10 tooth .200 pitch timing pulley to a 3/8 shaft on my
servo motor. I bored the pulley yesterday before I noticed there's not
enough meat left for a key, let alone set screws.

Anyway, I'm looking for a way to mount this pulley. Press fit? silver
solder? I've got NO experience with silver solder, which kind? Other ideas?

Karl