There are plastic overlays and complete dash pads available for 122s and 1800s, but I don't know if there are any for the PV. The covers are reasonably priced, but the complete pads are quite expensive.

My idea, that I came up with years ago when I owned a PV, (though I never actually tried it) is to carve a replica of the original, minus the grooves, out of balsa wood, and cover it with matte black vinyl. This would provide much of the crash padding of the original foam (balsa wood being quite soft) add little if any weight compared to the stock item, and has the potential to look very close to original, depending on one's carving skills. In my case, I was thinking of making a larger hood to fit a custom instrument cluster (with a round speedometer and a tach) that I was going to install (that didn't happen either) Possible difficulties with this idea include getting a large enough piece of balsa, (you would probably have to glue several pieces together) finding a suitable adhesive for the vinyl that wouldn't come unglued from the heat of the sun beating down on it, and that it would take a lot of time to make.

It might be a better plan to use a block of foam, in which case you would have to find something of a suitable density and strength, but at least you could probably get it in one piece. One of the stronger 3M spray contact adhesives (the kind used for headliners) might be suitable.