This thread is awesome - I found it years ago and finally got around to doing my 1980 ZX dash. I used the same SEM products mentioned in the original page of this thread and they've worked great. I ended up doing the textture coat twice though, and NOT knocking it down - knocking it down showed too many blemishes and, hey, it's different now
Tracking down some replacement center gauge bezels right now, as mine's tabs cracked when I removed them - after that, it's in with the dash - I'm really liking it and will post photos once in the car (plus the "before" photos). This took me a long time but with patience anyone can do it!