My dash was covered in soft vinyl by previous owner and the stitching was rotting so its time to get it fixed up. The original hard vinyl had been completely removed. Dash Doctor said they cant do it without the hard vinyl in place. Dash original initially quoted $795 or more depending on condition so I sent them some pics. Quote was then about $1500. For me about means probably more. I found online a 260z forum where guys have been fixing their cracked dashes so I though I would give it a try.
step 1. use expanding foam to fill holes and cracks. Sand back and repeat.
step 2. fit and check fitup.
step 3. paint with plastic bumper primer with high build thinner ratio. Next job.
The trick is to paint it with some orange peel to get the vinyl look.
Plan B, if it turns pear shaped recover it in leather.