I couldn't keep up covering the cracks with electrical tape in my original dash. I'd cover one crack and another just kept appearing. I finally broke down and ordered a 914Rubber replacement dash and I just finished installing it. It was about a half a day job. Yes, it was a PIA and my big hands are scraped up to prove it.
If I could give Mark one tip on his dashes (like he needs my help), it would be to make the dash studs out of metal and the nuts out of nylon. The replacement dash comes with nylon studs molded in and metal nuts supplied. If you are not ever so careful, with your hands in the dash upside down and backwards, you can easily cross thread these nylon studs. Ask me how I know.
Even inserting the new dash into initial position can scrape the threads on the studs as they pass through the sheet metal dash support slots. If the studs were made of metal and the nuts were nylon, then if you cross thread, at worst you would just mess up a nylon nut. It would also be a lot easier to start the nuts properly on metal stud threads too. Just my two cents......
Old Dash:
Click to view attachment
New Dash:
Click to view attachment