It was about 10 years ago now, so I can't remember exactly what I used. I just worked out the most suitable sized head and went to the local hardware store and bought some short screws with wide heads that looked about right. Nothing technical at all. In fact it turns out I used a mixture of original and new screws as the holes weren't evenly spaced.
Very much a bodge job, and I'd do a lot better today. But it was very cheap neck from eBay and I couldn't be bothered to remove the fake Custom Shop decal.