For the dash I would repair it as follows:
1. Taper the endges of the holes about 1" back from the edge. The taper should go from the full thickness of the dash on one edge of the taper to paper thin on the hole side of the taper.
2. Using duct tape, tape pieces of wax paper on the back of the dash so the wax paper is the only thing that is exposed through the holes. You can clamp a piece of wood to the back of the dash to give the wax paper some support. This will make step 3 a little easier.
3. Lay in matt and resin into the holes. Build the repair slightly higher than the existing dash.
4. When cure use some 80 grit on a DA and sand the dash flat.
5. You can choose to give it a light skim coat with a quality filler and then sand and finish with a high build primer.
Here is a Manx dash that I repaired. Its ABS plastic but I used the same steps I just outlined.