I know the stripes match and so does the "C". Beaten to hell and back. Looks legit. I found some pics online and all of the dimensions of the C and the width of the stripes seem to match. The C on the side of the helmets are all in different positions and sometimes of the rivets, so I know they were decals, like the helmet I have. Has "Riddell" on the side of the face-mask, but is very worn. If you look close enough, there is a repair on one of the suspension bands. Evidence seems to support it as game used.
Here are some photos of the '69 season.
Here are the pictures of the helmet.
Did buy new jaw pads because it did not have any. Need to get a chinstrap.
Seems legit to me.