Help installing a dash pad

[65-72 chevytoys]

Any ideas on installing a new dash pad on a 72. The new dash pad has the bolts installed on the back side of the pad, but along the top of the dash it looks like the old bolts are still in the dash and look like they need to be drilled out. THere is just a smooth head on the bolts that are still in the dashwith no nuts on the backside under the dash. Anyone run into this problem before? How did you do it?