Steel Valve covers VS Aluminum

I like retro M/T covers. I have a nicely polished set ready to go. They bring back some nostalgia for me, I had them on a '71 'Cuda 340 pistol grip car I should have never sold. Family came first, I had to sell it. I did pick up both kids from the hospital after they were born with it. The nurses just shook there heads. It ran low 11's and the whole car shook at idle. The kids did love it though.