JUSTABOF the additional protection depends of how many times (and the velocity) you are going to hit the ground. I´m sure they would have resist the crash (it was on asphalt about 40 mph), but is more easy is to replace this sheet added that repair the scratches in the original.
I cut a sheet of the size (not all just about 3/4) of the original, fit the contour with a nylon hammer, make some cuts for "air cooling", and some holes to fit the two pieces with rivets. Before to put the rivets, I smeared Pattex/Nural 21 between the pieces, and then the rivets to make pression. Finally I put hight temperature silicone (Würth) as cushion betwen the protector and the cylinder head.
In the photo '67 you can see that two ribons broke, and one screw finished bent.
(Sorry for my english)