Welcome to the site! I took a quick look at the headers that you linked. I would not feel comfortable making a recomendation, as I don't have a Yenko. I would however suggest that you visit the web site for firts gen Camaros,
www.camaros.net. The guys there will be able to answer any question you have about fittment. It will make a difference if you have an automatic or stick, power steering, and there is the size of the tubes. It will depend on the modifications that you have to the engine as to the tube size that will work best for you.