Dude those are the worst covers ever made, send um to me and I'll dispose of them properly!! Naw I think yer right on the years. I'm sure there 2 or 3 yer only covers, but they will fit all year nailheads. And they are by far my fovorites, espeiclally chromed!!
You are correct on the years and engine size. I have the set off my car planning on getting them chromed and add the factory decal so I can ditch the stock 401 valve covers I have on it now.