My 390 very late 67 car was stapled just lilke yours. I cleaned up the holes a bit but the repro staples fit perfectly using the method you, Cmayna, and I talked about punching through the rubber with a big needle in a small pair of vice grips. Bending the bottom was the hard part.
I am with the others, everything I have read is only 6 cylinders and Big Blocks got them.