Ok the burning question was keeping me awake and I needed to pull the headbadge eventually anyway so I went out and pulled the headbadge from the Bottecchia sitting in the garage. It was quite easy. For the record, it was attached at the factory with brass drive screws. They protruded just a bit into the head tube. I took a big flat-blade screwdriver and gently pushed on the back of the drive screws. They popped out about a couple of millimeters or so, enough that I could use a pair of wire cutters to leverage the screw out the rest of the way without damaging the badge (no I wasn't cutting on the screws, the wire cutters just had a perfect shape to get behind the head of the screw without scratching the badge) . So I'm planning to put it back in the same way. The dimensions (roughly, my cheap micrometer isn't that acurate) are:

overall length: 4.6mm
head diameter: 3.1mm
shaft diameter: 2.0mm

I think that is this standard drive screw size:
Decimal Size .075"
Shank Type Spiral
Head Diameter .127"
Head Height .049"
Recommended Hole Size (Drill No.) .067
Length 1/8" (not counting the head)

Unfortunately I've only seen steel, stainless steel and zinc plated drive screws online so far.