[70 ls6 convert]

I found my build sheet on the tank of my 69 z,by accident,for the life of me,i could not get the 302 to quitt fouling plugs,the year was 1988,I asked my shop helper to pull the tank and drain the old fuel,sence it was sitting for a few years,he yelled across the shop whats this piece a paper on the tank? sure enough it was a build sheet,We carfully just pulled it up and slid a putty knife under to help pull it off, it worked slick!! I still have the car and it still fouls plugs?