I had a number of splits, cracks, and dents in my '68 dash. It was probably the original dash. I didn't want to spend the kind of money the aftermarket folks demand, so I went the route of repairing what was broken. It might not hold up after I'm finished and it sits out in the sun for a while. But, for now, it looks OK.
I cut out the bad spots with a razor knife and filled the holes with bondo. After sanding and shaping the bondo, I sprayed it with a rattle can of "hammered finish" paint to duplicate the texture of the old vinyl. Then, I painted the whole thing with satin black. Like I said, I don't know how its going to stand up to the sun, but its a low budget job, and it'll look pretty fair if done with patience and care.