Whatever you do consider these:

1. Do no damage.

Do not enlarge the holes, flare the edges of the holes in the head tube, thread the holes,...

2. Make it removable by the next guy.

It should either be soluble or sliceable. Silicone adhesives strong enough and can be sliced off using a wire/fishing line slipped between the head tube and the badge. Alcohol or water as a lubricant helps a lot. Certain adhesives are soluble and can be dissolved away, releasing the badge.