I had those exact headers on my 64. If you have a 440 maybe I'd say go for it. Don't waste your money if you have a 383-400 block. They hit everywhere. Pan rails, trans pan rail, drag link, Starter... Mine had less than 60 miles on them. I cut them up with a sawzall and put manifolds back on. Not worth the hassle.
Are the engines really that different? That it would make fitment that much worse.